Jpeg File size mystery

NW
Posted By
norris_watkins
Jun 19, 2007
Views
1223
Replies
27
Status
Closed
I have a canon 6.3 MP DSLR ( Digital rebel ) camera, that produces jpeg files of the size approx 3-4 Mbytes.
But if I open one of these files in photoshop elements and resave it as jpeg ( I know I shouldnt resave jpegs ), the new file is about 500 kb. ( in the default good quality of 8 ).
Even if I choose the best jpeg quality ( 10 ) the file is still only about 700 kb.

When I check the quality of the produced jpegs, by zooming the picture to huge sizes, I dont see much difference in the quality. ( Even the exif data – camera model, shutter speed, date etc – are preserved )

Is it possible that the camera didnt have much horsepower to do a good job with the compression, so that it ended it with a big file that was not much compressed. If that is true then I can save some hard disk space by recompressing the images.

thanks
–nw
R
ronviers
Jun 19, 2007
On Jun 19, 5:10 pm, wrote:
I have a canon 6.3 MP DSLR ( Digital rebel ) camera, that produces jpeg files of the size approx 3-4 Mbytes.
But if I open one of these files in photoshop elements and resave it as jpeg ( I know I shouldnt resave jpegs ), the new file is about 500 kb. ( in the default good quality of 8 ).
Even if I choose the best jpeg quality ( 10 ) the file is still only about 700 kb.

When I check the quality of the produced jpegs, by zooming the picture to huge sizes, I dont see much difference in the quality. ( Even the exif data – camera model, shutter speed, date etc – are preserved )
Is it possible that the camera didnt have much horsepower to do a good job with the compression, so that it ended it with a big file that was not much compressed. If that is true then I can save some hard disk space by recompressing the images.

thanks
–nw

Hi nw,
What are the pictures of? How they compress will depend a lot on things like noise, spatial detail, exposure, DoF etc. Take a picture of a piece of concrete, it will not compress much.

Ron
NW
norris_watkins
Jun 19, 2007
On Jun 19, 6:33 pm, "" wrote:
On Jun 19, 5:10 pm, wrote:

I have a canon 6.3 MP DSLR ( Digital rebel ) camera, that produces jpeg files of the size approx 3-4 Mbytes.
But if I open one of these files in photoshop elements and resave it as jpeg ( I know I shouldnt resave jpegs ), the new file is about 500 kb. ( in the default good quality of 8 ).
Even if I choose the best jpeg quality ( 10 ) the file is still only about 700 kb.

When I check the quality of the produced jpegs, by zooming the picture to huge sizes, I dont see much difference in the quality. ( Even the exif data – camera model, shutter speed, date etc – are preserved )

Is it possible that the camera didnt have much horsepower to do a good job with the compression, so that it ended it with a big file that was not much compressed. If that is true then I can save some hard disk space by recompressing the images.

thanks
–nw

Hi nw,
What are the pictures of?

These are pretty ordinary pictures like our family members, birds, bridges etc.
I understand that each of them compresses differently. But I dont understand why there should be such a big difference between the camera compression and photoshop.
Actually even MS Paint compresses it comparable to PS.

I m wondering if there is any difference in chroma subsampling etc.

By the way when I right click one of these pictures in windows explorer and look at the properties, I see that they have the bit depth as 24 as expected.

But if I look at the properties->meta data->exif data in PS, I see that the bit depth is 8 bits.
So Im confused even more.

–nw
NW
norris_watkins
Jun 19, 2007
By the way when I right click one of these pictures in windows explorer and look at the properties, I see that they have the bit depth as 24 as expected.

But if I look at the properties->meta data->exif data in PS, I see that the bit depth is 8 bits.

‘Sorry I meant properties->meta data->File properties’ here

–nw
T
Tacit
Jun 19, 2007
In article ,
wrote:

By the way when I right click one of these pictures in windows explorer and look at the properties, I see that they have the bit depth as 24 as expected.

But if I look at the properties->meta data->exif data in PS, I see that the bit depth is 8 bits.
So Im confused even more.

Photoshop and Windows Explorer both agree.

Photoshop shows you 8 bits. 8 bits per channel times 3 channels (RGB) = 24 bits. Photoshop shows you the number of bits per channel; Explorer shows you the number of bits per pixel.


Photography, kink, polyamory, shareware, and more: all at http://www.xeromag.com/franklin.html
B
beu
Jun 20, 2007
In article ,
wrote:
I have a canon 6.3 MP DSLR ( Digital rebel ) camera, that produces jpeg files of the size approx 3-4 Mbytes.
But if I open one of these files in photoshop elements and resave it as jpeg ( I know I shouldnt resave jpegs ), the new file is about 500 kb. ( in the default good quality of 8 ).
Even if I choose the best jpeg quality ( 10 ) the file is still only about 700 kb.

When I check the quality of the produced jpegs, by zooming the picture to huge sizes, I dont see much difference in the quality. ( Even the exif data – camera model, shutter speed, date etc – are preserved )
Is it possible that the camera didnt have much horsepower to do a good job with the compression, so that it ended it with a big file that was not much compressed. If that is true then I can save some hard disk space by recompressing the images.

thanks
–nw

I have the same camera and have noticed that the original Rebel routinely produces ‘bloated’ jpg images when shooting Medium resolution. A couple of years ago I downloaded a copy of PhotoMan by Keith Sheppard to analyze all the components of the jpg files produced and found that the images contained a lot of ‘dead wood’ — thousands of bytes of data that wasn’t part of the jpg image or part of the EXIF tags.

You can download a (free) copy of Keith Sheppard’s PhotoMan application from:
http://homepages.tesco.net/~Keith.Sheppard/photoman/home.htm Use it to compare a before and after image.

My solution to remove the ‘dead wood’ is to use IrfanView’s lossless jpg transformations, selecting the transformation option of "None". As the option says, it "can be used for optimizing and cleaning" — exactly what it does for me.
J
Jim
Jun 20, 2007
wrote in message
On Jun 19, 6:33 pm, "" wrote:
On Jun 19, 5:10 pm, wrote:

I have a canon 6.3 MP DSLR ( Digital rebel ) camera, that produces jpeg files of the size approx 3-4 Mbytes.
But if I open one of these files in photoshop elements and resave it as jpeg ( I know I shouldnt resave jpegs ), the new file is about 500 kb. ( in the default good quality of 8 ).
Even if I choose the best jpeg quality ( 10 ) the file is still only about 700 kb.

When I check the quality of the produced jpegs, by zooming the picture to huge sizes, I dont see much difference in the quality. ( Even the exif data – camera model, shutter speed, date etc – are preserved )

Is it possible that the camera didnt have much horsepower to do a good job with the compression, so that it ended it with a big file that was not much compressed. If that is true then I can save some hard disk space by recompressing the images.

thanks
–nw

Hi nw,
What are the pictures of?

These are pretty ordinary pictures like our family members, birds, bridges etc.
I understand that each of them compresses differently. But I dont understand why there should be such a big difference between the camera compression and photoshop.
Actually even MS Paint compresses it comparable to PS.

I m wondering if there is any difference in chroma subsampling etc.
By the way when I right click one of these pictures in windows explorer and look at the properties, I see that they have the bit depth as 24 as expected.
Total number of bits is 8 * 3
But if I look at the properties->meta data->exif data in PS, I see that the bit depth is 8 bits.
So Im confused even more.
8 Bits per channel. 3 Channels times 8 bits per channel results in 24 bits per pixel.
Jim
–nw

NS
Nicholas Sherlock
Jun 20, 2007
Bruce Uttley wrote:
[…] A couple of years ago I downloaded a copy of
PhotoMan by Keith Sheppard to analyze all the components of the jpg files produced and found that the images contained a lot of ‘dead wood’ — thousands of bytes of data that wasn’t part of the jpg image or part of the EXIF tags.

This is probably the camera’s stored thumbnail of the image, so that it can browse images quickly on the camera.

Cheers,
Nicholas Sherlock
NW
norris_watkins
Jun 20, 2007
On Jun 19, 11:31 pm, Nicholas Sherlock wrote:
Bruce Uttley wrote:
[…] A couple of years ago I downloaded a copy of
PhotoMan by Keith Sheppard to analyze all the components of the jpg files produced and found that the images contained a lot of ‘dead wood’ — thousands of bytes of data that wasn’t part of the jpg image or part of the EXIF tags.

This is probably the camera’s stored thumbnail of the image, so that it can browse images quickly on the camera.

Thank you very much for the responses.
Both dead wood and thumpnails sounds very plausible.

Thanks Bruce for the tip in irfanview. Yes when I did the lossless compression with ‘none’, I managed to get the size reduced by about 15%. ( A 2400 kb file became 2000 kb )
But nothing compared to the huge savings I was seeing with the ‘save as’ of photoshop. ( 2400 kb file becoming 650 kb )

At this point Im wondering if it is even possible to produce the exact same quality jpegs with different compression ratios.
I mean how can I verify that the quality has not suffered when I did a ‘save as’

Thanks again also for the clarification on 8 bits vs 24 bits –nw
TE
Toke Eskildsen
Jun 20, 2007
wrote:

At this point Im wondering if it is even possible to produce the exact same quality jpegs with different compression ratios.

Not normally. But it’s simple to show that it can be done. The trivial case is a one-pixel image, saved at different compression ratios.

I mean how can I verify that the quality has not suffered when I did a ‘save as’

One way is to use the tool compare from the freeware suite ImageMagick. This will give you a measurement for the difference between two images.

Another way is to put the images on top of each other as layers, then subtract them and look for noise. You might want to do a levels adjustment to make the difference more visible.

A third way is simple: Put the images on top of each other in different windows, so that they align exactly. Then switch back and forth with alt-tab.

As for your original question: JPEGs are made to benefit from specialised hardware. Your camera probably has more horsepower that your computer, when it comes to JPEG compression.

I must admit that I am not familiar with Photoshop Elements, but compressing 6.3MP down to 700KB sounds like an optimisation towards screen viewing, rather than archival or big format prints. —
Toke Eskildsen – http://ekot.dk/
J
Joe
Jun 20, 2007
wrote:

I have a canon 6.3 MP DSLR ( Digital rebel ) camera, that produces jpeg files of the size approx 3-4 Mbytes.
But if I open one of these files in photoshop elements and resave it as jpeg ( I know I shouldnt resave jpegs ), the new file is about 500 kb. ( in the default good quality of 8 ).
Even if I choose the best jpeg quality ( 10 ) the file is still only about 700 kb.

When I check the quality of the produced jpegs, by zooming the picture to huge sizes, I dont see much difference in the quality. ( Even the exif data – camera model, shutter speed, date etc – are preserved )
Is it possible that the camera didnt have much horsepower to do a good job with the compression, so that it ended it with a big file that was not much compressed. If that is true then I can save some hard disk space by recompressing the images.

I don’t have PS Element to know what you are doing at you end, so why not give the *exact* option at your end see if I (we) can be able to figure out what you do wrong. Also, in general

– CD/DVD is so cheap these days and good family memory can be priceless for the next generation(s), so I would suggest to keep the original and the retouched version. And save as HIGHEST

– And *if* you save as HIGHEST QUALITY then the size should either about the same, and usually *larger* than the original (unless you crop and reduce the quality).

thanks
–nw
M
Mike
Jun 21, 2007
In article , says…
wrote:

At this point Im wondering if it is even possible to produce the exact same quality jpegs with different compression ratios.

Not normally. But it’s simple to show that it can be done. The trivial case is a one-pixel image, saved at different compression ratios.
I mean how can I verify that the quality has not suffered when I did a ‘save as’

One way is to use the tool compare from the freeware suite ImageMagick. This will give you a measurement for the difference between two images.
Another way is to put the images on top of each other as layers, then subtract them and look for noise. You might want to do a levels adjustment to make the difference more visible.
if you put one on top of the other then the difference mode is useful to see where the biggest effect is.
T
Tacit
Jun 21, 2007
In article ,
wrote:

At this point Im wondering if it is even possible to produce the exact same quality jpegs with different compression ratios.
I mean how can I verify that the quality has not suffered when I did a ‘save as’

You can’t. The quality DID suffer.

If you open a JPEG and then do a Save As, the JPEG is compressed again. Every time you do this, the quality goes down. The loss of quality is always cumulative with each successive iteration; if you open the JPEG and the save it again, you lose more quality; open and save again, you lose still more quality; and so on.

If you care about quality, don’t use JPEG.


Photography, kink, polyamory, shareware, and more: all at http://www.xeromag.com/franklin.html
J
Joe
Jun 21, 2007
tacit wrote:

In article ,
wrote:

At this point Im wondering if it is even possible to produce the exact same quality jpegs with different compression ratios.
I mean how can I verify that the quality has not suffered when I did a ‘save as’

You can’t. The quality DID suffer.

If you open a JPEG and then do a Save As, the JPEG is compressed again. Every time you do this, the quality goes down. The loss of quality is always cumulative with each successive iteration; if you open the JPEG and the save it again, you lose more quality; open and save again, you lose still more quality; and so on.

If you care about quality, don’t use JPEG.

Losing quality may not be the exact word (even I have been hearing this for ages), or the color of some pixel may chance a little. And it was nearly a decade ago when I tested a low quality JPEG, and software these days are better as well as most digital cameras have much higher resolution than decade ago. IOW, few thousands of pixels with color changing a little may not effect 9-12+MP image.

So, I would suggest to find a good graphic program (like Photoshop or similar) then copy a 8-10MP image over and over several times, then ZOOM IN the original and the last saved 500-600% (or whatever) til you see the square-blocks, and see for yourself.

Yes, some poor graphic program’s may lose lot of quality (you can see with your own eye) but not all graphic programs.
JB
John Boy
Jun 21, 2007
Joe wrote:

Yes, some poor graphic program’s may lose lot of quality (you can see with your own eye) but not all graphic programs.

JPEG is a standard, and easy to code. I see no reason the results should be different with any program.
J
Joe
Jun 21, 2007
John Boy wrote:

Joe wrote:

Yes, some poor graphic program’s may lose lot of quality (you can see with your own eye) but not all graphic programs.

JPEG is a standard, and easy to code. I see no reason the results should be different with any program.

JPEG is standard but the programmer isn’t, and that’s why different program gives different result, and that’s why some dreamers say PSP is just as good as Photoshop but 1/6 the price <bg>. And I didn’t think it would make much or any difference til around 7-8+ years ago I messed around with a cheapie graphic program called something like Magix (something ???) and I saw it destroyed the image right before my eyes. I couldn’t believe it so I saved different graphic at Max Quality and the screen was filled with artifacts (didn’t even need to zoom in to see them).

Same with RAW converter (even between LightRoom, ARC v3.x, ARC v4.x and Photoshop) they don’t give the same result. And I only talking about some color, contrast, explosure, noise etc..
D
Dave
Jun 21, 2007
if you put one on top of the other then the difference mode is useful to see where the biggest effect is.

If you care about quality, don’t use JPEG.

IOW, few thousands of pixels with color changing a little may not effect 9-12+MP image.

yes, some poor graphic program’s may lose lot of quality (you can see with your own eye) but not all graphic programs.

JPEG is a standard, and easy to code. I see no reason the results should be different with any program.

JPEG is standard but the programmer isn’t, and that’s why different program gives different result, and that’s why some dreamers say PSP is just as good as Photoshop but 1/6 the price <bg>.

A few years ago I was involved in a discussion whether jpg’s also lose value when getting moved. I said yes, and the other guys said no. And that is where we left it.

Moving between files may be different, but moving from one drive to another, is still nothing less than copy to one drive and deleting on the other.

How many of you guys take the images to the printer on a memory stick? I mean, it is not practical to use a CD every time, when sometimes (like my intentions for tomorrow) is to have about 20 jumbos ( 4 x 6 inch or 100 x 150 cm’s) and two A4’s printed.

If this was for framing or for a newspaper, I would have had it done from Tiffs, but this is simply for once in a while casual viewing, so it will be done from jpg’s.

Dave
TE
Toke Eskildsen
Jun 21, 2007
Joe wrote:

So, I would suggest to find a good graphic program (like Photoshop or similar) then copy a 8-10MP image over and over several times, […]

It’s an old experiment, which sounds intuitive, but gives misleading results: Most, if not all, JPEG-encoders converge to a stable image when you recompress the same image over and over. By far the biggest loss in quality happens at the first save, while subsequent recompressions introduces less and less noise.

If the sun is in the right direction and you diety of choice smiles upon you, you might be able to contact my webserver and see this demonstrated at http://ekot.dk/misc/recompress2/

This means that the experiment you outline will apparently demonstrate that there are no real problem with using JPEG as a working format, while the truth is (fortunately) what we all are told: That there will be significant cummulative losses.

If the compression settings are tweaked between recompressions or if the image is changed between saves (e.g. adjusting brightness and such), the losses will continue to be significant.

As for the losses themselves, I find that a much overlooked aspect of JPEG recompression is the dulling of colors. The noise is easy to see, but we tend not to notice when the colors are just a little less bright, compared to the previous version.

Toke Eskildsen – http://ekot.dk/
S
sonyantony
Jun 22, 2007
I ve been reading this interesting thread.
Since I too used to use the same camera, I decided to try this out. Yes there is a 5 fold size reduction when you do a ‘save as’ in photoshop, or MS paint.
I have uploaded the pictures to my webserver.
http://bellsouthpwp2.net/s/o/sonyantony/
It will be great if somebody can look at these pictures and explain.

–sony
GH
Gernot Hoffmann
Jun 22, 2007
schrieb:
I ve been reading this interesting thread.
Since I too used to use the same camera, I decided to try this out. Yes there is a 5 fold size reduction when you do a ‘save as’ in photoshop, or MS paint.
I have uploaded the pictures to my webserver.
http://bellsouthpwp2.net/s/o/sonyantony/
It will be great if somebody can look at these pictures and explain. –sony

3072 x 2048 pixels = 18 MBytes TrueColor.
Original JPEG: 6 MBytes. Compression ratio only 3.
Photoshop JPEG: 2 MBytes. Compression ratio 9.

Color subsampling delivers already a compression ratio 2. The color information is averaged for four adjacent pixels. A further compression by 1.5 is not worth the effort.
Even without color subsampling: a JPEG compression
ratio 3 is too low. Ratio 2..3 can be achieved by
lossless TIFF compression.

With color subsampling (mostly standard):
Ratio = 5: very good quality
Ratio =10: good quality
Ratio =20: good Web quality

Both files contain the sRGB ICC profile, which consumes
only 3kBytes.

http://www.fho-emden.de/~hoffmann/jpeg131200.pdf

Best regards –Gernot Hoffmann
J
Joe
Jun 22, 2007
Dave wrote:

if you put one on top of the other then the difference mode is useful to see where the biggest effect is.

If you care about quality, don’t use JPEG.

IOW, few thousands of pixels with color changing a little may not effect 9-12+MP image.

yes, some poor graphic program’s may lose lot of quality (you can see with your own eye) but not all graphic programs.

JPEG is a standard, and easy to code. I see no reason the results should be different with any program.

JPEG is standard but the programmer isn’t, and that’s why different program gives different result, and that’s why some dreamers say PSP is just as good as Photoshop but 1/6 the price <bg>.

A few years ago I was involved in a discussion whether jpg’s also lose value when getting moved. I said yes, and the other guys said no. And that is where we left it.

The JPEG vs other Mighty God has been going on for nearly 2 decades, and many just pass what they read/heard from other like a word of bible without knowing what has been going on.

Moving between files may be different, but moving from one drive to another, is still nothing less than copy to one drive and deleting on the other.

Years ago, some claimed that the quality of his photos on CD got faded away because the life of CD was getting shorter etc. And yup! I have read some experted passing the value experience to others by saying copying JPG (not saving) from one drive to other will degrade the quality <bg>

How many of you guys take the images to the printer on a memory stick? I mean, it is not practical to use a CD every time, when sometimes (like my intentions for tomorrow) is to have about 20 jumbos ( 4 x 6 inch or 100 x 150 cm’s) and two A4’s printed.

My inkjet printer has built-in memory card reader and it can print without computer, but I haven’t printed any without going through Photoshop none for me so far. *BUT* these days with many cheap small printer that can print directly from camera or memory stick, and some stores have machine with Scanner and Printer they accept memory stick and CD etc.. so the answer is YES

If this was for framing or for a newspaper, I would have had it done from Tiffs, but this is simply for once in a while casual viewing, so it will be done from jpg’s.

Still no TIFF for me, cuz I don’t save and save and save the same JPG over and over, and with 9-10+GP a slightly color changing of few pixels won’t make me sweated so TIFF ain’t in my dictionary <bg>

Dave
J
Joe
Jun 22, 2007
Toke Eskildsen wrote:

Joe wrote:

So, I would suggest to find a good graphic program (like Photoshop or similar) then copy a 8-10MP image over and over several times, […]

It’s an old experiment, which sounds intuitive, but gives misleading results: Most, if not all, JPEG-encoders converge to a stable image when you recompress the same image over and over. By far the biggest loss in quality happens at the first save, while subsequent recompressions introduces less and less noise.

If the sun is in the right direction and you diety of choice smiles upon you, you might be able to contact my webserver and see this demonstrated at http://ekot.dk/misc/recompress2/

I sure can see the difference *but* I don’t know what the heck the guy did at his end. And of course I won’t buy his story unless I know he knows what I is going or I know what he did to the test etc..

Why don’t you try it yourself, and it wouldn’t take more than some seconds (to make the copying), or 1-2 minutes to compare the difference

1. Start with a good quality image. Just don’t use RAW converter or anything to blow up any color channel, or chaging the sharpness, noise etc.. Of course unless you know exactly what to do, then it may be another story (IOW, I am saying to PUBLIC not directly to you or any specific)

This means that the experiment you outline will apparently demonstrate that there are no real problem with using JPEG as a working format, while the truth is (fortunately) what we all are told: That there will be significant cummulative losses.

You may not want to live with what you are told to live your life, but you may want to try thing your own.

If the compression settings are tweaked between recompressions or if the image is changed between saves (e.g. adjusting brightness and such), the losses will continue to be significant.

If you have problem then you may want to learn some trick or skill to overcome the problem. And when you say "compression" which doesn’t mean much or anything, because it will depend on your technique, compression level, and program you use etc..

As for the losses themselves, I find that a much overlooked aspect of JPEG recompression is the dulling of colors. The noise is easy to see, but we tend not to notice when the colors are just a little less bright, compared to the previous version.

And I am guessing you are telling me about the NOISE based on the samples you see at the web? Me? just by looking at the samples I can smell something ain’t right <bg>
TE
Toke Eskildsen
Jun 24, 2007
Joe wrote:

Toke Eskildsen wrote:
If the sun is in the right direction and you diety of choice smiles upon you, you might be able to contact my webserver and see this demonstrated at http://ekot.dk/misc/recompress2/

I sure can see the difference *but* I don’t know what the heck the guy did at his end.

I am "that guy" and I wrote what I did on the page under the heading "Methodology". If you read that part, I’d be happy to clarify any specific questions to it, here as well as on the web page.

(checking…)

I see that the webserver refused to show the Tcl-script I used. That is fixed now.

Toke:
This means that the experiment you outline will apparently demonstrate that there are no real problem with using JPEG as a working format, while the truth is (fortunately) what we all are told: That there will be significant cummulative losses.

You may not want to live with what you are told to live your life, but you may want to try thing your own.

In your newfound knowledge that I am in fact the author of the page you’re referring to above, do you have any elaborations for your snide comment above? Maybe "Whoops… I messed up. Sorry about trying to belittle you, when you in fact did try things out on your own"?

Toke:
If the compression settings are tweaked between recompressions or if the image is changed between saves (e.g. adjusting brightness and such), the losses will continue to be significant.

If you have problem then you may want to learn some trick or skill to overcome the problem.

The JPEG FAQ disagrees with you:
http://www.faqs.org/faqs/jpeg-faq/part1/section-10.html
Could you elaborate, please?

And when you say "compression" which doesn’t mean much or anything, because it will depend on your technique, compression level, and program you use etc..

Just as "then copy a 8-10MP image over and over several times" doesn’t make sense? It’s a matter of detail-level in the discussion.

And I am guessing you are telling me about the NOISE based on the samples you see at the web? Me?

I have no idea about who you are, outside of this thread. Judging by your exceedingly bad manners, I’ll assume that you consider yourself very knowledgeable in this area.

just by looking at the samples I can smell something ain’t right <bg>

What’s wrong with the samples then? Don’t you find them representative for the kind of images JPEG is used for (with the obvious excemption of course)?

Or is this an "The guy don’t know how to take good photos, so it’s a sure thing that he messes up in the technical department too"-thing? —
Toke Eskildsen – http://ekot.dk/
J
Joe
Jun 25, 2007
Toke Eskildsen wrote:

Joe wrote:

Toke Eskildsen wrote:
If the sun is in the right direction and you diety of choice smiles upon you, you might be able to contact my webserver and see this demonstrated at http://ekot.dk/misc/recompress2/

I sure can see the difference *but* I don’t know what the heck the guy did at his end.

I am "that guy" and I wrote what I did on the page under the heading "Methodology". If you read that part, I’d be happy to clarify any specific questions to it, here as well as on the web page.

How do you come up with the fancy NOISE that I have can’t figure out how you did it. Also, noise alone already blew my mind away, but sharpest noise I have ever seen really got me good.

Or anyone who wants to find out the difference just making the dupe of original 5-10 times (save to BEST) and they can see for themselves.

(checking…)

I see that the webserver refused to show the Tcl-script I used. That is fixed now.

Toke:
This means that the experiment you outline will apparently demonstrate that there are no real problem with using JPEG as a working format, while the truth is (fortunately) what we all are told: That there will be significant cummulative losses.

You may not want to live with what you are told to live your life, but you may want to try thing your own.

In your newfound knowledge that I am in fact the author of the page you’re referring to above, do you have any elaborations for your snide comment above? Maybe "Whoops… I messed up. Sorry about trying to belittle you, when you in fact did try things out on your own"?

I still wondering how you come up with those fancy noise. I bet most folks here can try and have the same question.

Toke:
If the compression settings are tweaked between recompressions or if the image is changed between saves (e.g. adjusting brightness and such), the losses will continue to be significant.

If you have problem then you may want to learn some trick or skill to overcome the problem.

The JPEG FAQ disagrees with you:
http://www.faqs.org/faqs/jpeg-faq/part1/section-10.html
Could you elaborate, please?

And when you say "compression" which doesn’t mean much or anything, because it will depend on your technique, compression level, and program you use etc..

Just as "then copy a 8-10MP image over and over several times" doesn’t make sense? It’s a matter of detail-level in the discussion.
And I am guessing you are telling me about the NOISE based on the samples you see at the web? Me?

I have no idea about who you are, outside of this thread. Judging by your exceedingly bad manners, I’ll assume that you consider yourself very knowledgeable in this area.

You mean don’t believe what I see is bad manner? I haven’t said I am good/bad yet, but I would suggest other to copy their JPG several times to see the difference.

just by looking at the samples I can smell something ain’t right <bg>

What’s wrong with the samples then? Don’t you find them representative for the kind of images JPEG is used for (with the obvious excemption of course)?

What wrong? the sample just doesn’t smell right, and I can’t say it smells good <bg>

Or is this an "The guy don’t know how to take good photos, so it’s a sure thing that he messes up in the technical department too"-thing?

Do I have to agree with you to make you happy? You asked to look at the sample and I can’t find anything I can agree, and you are not happy because I don’t agree with you? <bg>
TE
Toke Eskildsen
Jun 25, 2007
Joe wrote:
How do you come up with the fancy NOISE that I have can’t figure out how
you did it. Also, noise alone already blew my mind away, but sharpest noise I have ever seen really got me good.

Are you talking about the normalised difference? Normalised means that the narrow band of murky colors making up the difference is stretched over the full spectrum, this making it easy to see where the noise is concentrated. It does not show how harsh the noise is, just the distribution – besides that, it acts as a guide of where to look in the normal pictures.

http://en.wikipedia.org/wiki/Normalization_%28image_processi ng%29

If that wasn’t it, you’ll have to be more specific in your questioning.

Or anyone who wants to find out the difference just making the dupe of original 5-10 times (save to BEST) and they can see for themselves.

That would demonstrate my point very well: That unchanged (besides the recompression) JPEG images stabilises. It’s also an unrealistic workflow and thus does not lead to any real-world use.

You mean don’t believe what I see is bad manner?

I am not stupid enough to fall for such a simple trick. Try again.

Now, you skipped my question about recompression with changes:

The JPEG FAQ disagrees with you:
http://www.faqs.org/faqs/jpeg-faq/part1/section-10.html
Could you elaborate, please?

I would like an answer there, if you have the time, as your observations are clearly different.

What’s wrong with the samples then? Don’t you find them
representative for the kind of images JPEG is used for (with the obvious excemption of course)?

What wrong? the sample just doesn’t smell right, and I can’t say it smells good <bg>

If you can’t put words to your gut feelings, you won’t change anything.

Or is this an "The guy don’t know how to take good photos, so it’s a sure thing that he messes up in the technical department too"-thing?

Do I have to agree with you to make you happy?

Sigh… You clearly passed "Dirty tricks in conversations 101" and took extensive notes, didn’t you?

When you don’t give me any more data that what you did, I try and discover what you mean by asking questions. As you see, my first question was whether the samples weren’t representative.

You asked to look at the
sample and I can’t find anything I can agree, and you are not happy because I don’t agree with you? <bg>

I an unhappy, because you aren’t capable of stating what is wrong with either my samples, methodology or conclusions. I am unhappy because you just repeat your proposal for an experiment, even though I have already tried it and even though I have explained why the experiment isn’t representative for real life working with images.

Toke Eskildsen – http://ekot.dk/
J
Joe
Jun 25, 2007
Toke Eskildsen wrote:

<snip>
You mean don’t believe what I see is bad manner?

I am not stupid enough to fall for such a simple trick. Try again.

I read people say "three times is the charm" <bg>. So, You mean don’t believe what I see is bad manner?
TE
Toke Eskildsen
Jun 25, 2007
Joe wrote:

Toke Eskildsen wrote:
I am not stupid enough to fall for such a simple trick. Try again.

I read people say "three times is the charm" <bg>. So, You mean don’t believe what I see is bad manner?

When did you stop beating your wife?

I do believe that you are not interested in reaching a conclusion. This discussion is over for now for my part. I’ll participate again, if you get back on track.

Toke Eskildsen – http://ekot.dk/
J
Joe
Jun 26, 2007
Toke Eskildsen wrote:

Joe wrote:

Toke Eskildsen wrote:
I am not stupid enough to fall for such a simple trick. Try again.

I read people say "three times is the charm" <bg>. So, You mean don’t believe what I see is bad manner?

When did you stop beating your wife?

I guess since I started beating you <bg>

I do believe that you are not interested in reaching a conclusion. This discussion is over for now for my part. I’ll participate again, if you get back on track.

No, I do interest in something I can learn, but don’t want to waste my time on thing has no value to me. I am guessing most people don’t find anything true from your sample, and I still don’t know how you can come up with that fancy noise.

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