Auto levels

il barbi wrote:

(I think
I’m puzzled with such operation: I apply auto levels to some jpgs from my digital camera (1600×1200 pixel), with file size about 600K, and I get file size about 300K!
Someone can explain?
il barbi

Your Photo Editing Program COMPRESSED your image more than it was originally.
In Photoshop, and probably others, you can choose the degree of compression you want in the SAVED image.
Tell us what photo Editor you are using and maybe someone can tell you how to control the compression.
I only know Photoshop, but many in this NG have used every imaginable photo editor. They can surely help you.
Bob Williams

"il barbi" wrote:

(I think
I’m puzzled with such operation: I apply auto levels to some jpgs from my digital camera (1600×1200 pixel), with file size about 600K, and I get file size about 300K!
Someone can explain?
il barbi

The question should be about the "SIZE" *not* "Auto Level" as Auto Level has nothing to do with the size decreasing.

The In/Decreasing size usually depend on the COMPRESSION. Or if you want to save at the best quality or largest size then tell Photoshop to save to quality 12 (I think 12 is the highest number), and if you want to reduce the size/quality then set to lower number lower than 12.

"Joe" wrote in message

"il barbi" wrote:

(I think
I’m puzzled with such operation: I apply auto levels to some jpgs from my digital camera (1600×1200 pixel), with file size about 600K, and I get file
size about 300K!
Someone can explain?
il barbi

The question should be about the "SIZE" *not* "Auto Level" as Auto Level has nothing to do with the size decreasing.

The In/Decreasing size usually depend on the COMPRESSION. Or if you want to save at the best quality or largest size then tell Photoshop to save to quality 12 (I think 12 is the highest number), and if you want to reduce the
size/quality then set to lower number lower than 12.

Basically you never want to keep saving jpg’s from jpg’s as with each compression the image will degrade (how much and if it is visible is a debate)(and one advantage of shooting RAW)

from camera if you have jpg save to a lossless format like TIF or PSD to make your changes then save copies from those

or as suggested save to a higher quality jpg if you must save jpg to jpg

"Bob Williams" ha scritto nel messaggio

il barbi wrote:

(I think
I’m puzzled with such operation: I apply auto levels to some jpgs from my digital camera (1600×1200 pixel), with file size about 600K, and I get file size about 300K!
Someone can explain?
il barbi

Your Photo Editing Program COMPRESSED your image more than it was originally.
In Photoshop, and probably others, you can choose the degree of compression you want in the SAVED image.
Tell us what photo Editor you are using and maybe someone can tell you how to control the compression.
I only know Photoshop, but many in this NG have used every imaginable photo editor. They can surely help you.
Bob Williams

Of course I’m using Photoshop, this is a NG about Photoshop, isn’t it? Now I get a file from my digital camera, say org.jpg, size 599K, 1600×1200 pixels = about 2Mpixels, I enter Photoshop, open org.jpg and choose autolevels, then file – close, it asks me "Save the modifications?", I choose yes and I get org.jpg with size 375K I thought it must have expanded the file as a bitmap, applied auto level by scaling the 3 RGB bytes representing each pixel, then re-compressed the file at the same degreee as at beginning (it did not ask me the jpg compression level)
but why is the size about halved?
il barbi

On Tue, 11 Aug 2009 23:53:18 +0200, "il barbi"

Now I get a file from my digital camera, say org.jpg, size 599K, 1600×1200 pixels = about 2Mpixels, I enter Photoshop, open org.jpg and choose autolevels, then file – close, it asks me "Save the modifications?", I choose yes and I get org.jpg with size 375K I thought it must have expanded the file as a bitmap, applied auto level by scaling the 3 RGB bytes representing each pixel, then re-compressed the file at the same degreee as at beginning (it did not ask me the jpg compression level)
but why is the size about halved?
il barbi

Barbi, this is very normal and vary from camera to camera. If I shoot a 9mpx photo with my Fiji Finepix s9600,
the size can be anything between 2.2 to 4.6 MB.
This is Fuji doing a high compression.

"Kabuki" wrote:

"Joe" wrote in message

"il barbi" wrote:

(I think
I’m puzzled with such operation: I apply auto levels to some jpgs from my digital camera (1600×1200 pixel), with file size about 600K, and I get file
size about 300K!
Someone can explain?
il barbi

The question should be about the "SIZE" *not* "Auto Level" as Auto Level has nothing to do with the size decreasing.

The In/Decreasing size usually depend on the COMPRESSION. Or if you want to save at the best quality or largest size then tell Photoshop to save to quality 12 (I think 12 is the highest number), and if you want to reduce the
size/quality then set to lower number lower than 12.

Basically you never want to keep saving jpg’s from jpg’s as with each compression the image will degrade (how much and if it is visible is a debate)(and one advantage of shooting RAW)

from camera if you have jpg save to a lossless format like TIF or PSD to make your changes then save copies from those

or as suggested save to a higher quality jpg if you must save jpg to jpg

That’s you not me as I never care to use TIFF, and JPG is more than enough to bring me $$$ so I rarely care for PSD either *unless* I need to work on some layer later.

il barbi wrote:

"Bob Williams" ha scritto nel messaggio

il barbi wrote:

(I think
I’m puzzled with such operation: I apply auto levels to some jpgs from my digital camera (1600×1200 pixel), with file size about 600K, and I get file size about 300K!
Someone can explain?
il barbi

Your Photo Editing Program COMPRESSED your image more than it was originally.
In Photoshop, and probably others, you can choose the degree of compression you want in the SAVED image.
Tell us what photo Editor you are using and maybe someone can tell you how to control the compression.
I only know Photoshop, but many in this NG have used every imaginable photo editor. They can surely help you.
Bob Williams

Of course I’m using Photoshop, this is a NG about Photoshop, isn’t it? Now I get a file from my digital camera, say org.jpg, size 599K, 1600×1200 pixels = about 2Mpixels, I enter Photoshop, open org.jpg and choose autolevels, then file – close, it asks me "Save the modifications?", I choose yes and I get org.jpg with size 375K I thought it must have expanded the file as a bitmap, applied auto level by scaling the 3 RGB bytes representing each pixel, then re-compressed the file at the same degreee as at beginning (it did not ask me the jpg compression level)
but why is the size about halved?
il barbi

After you do your Auto Levels operation.
Try the FILE >>> SAVE AS option and then select the highest quality. Check the number of pixels then.
Bob

"Bob Williams" ha scritto nel messaggio

il barbi wrote:

"Bob Williams" ha scritto nel messaggio

il barbi wrote:

(I think
I’m puzzled with such operation: I apply auto levels to some jpgs from my digital camera (1600×1200 pixel), with file size about 600K, and I get file size about 300K!
Someone can explain?
il barbi

Your Photo Editing Program COMPRESSED your image more than it was originally.
In Photoshop, and probably others, you can choose the degree of compression you want in the SAVED image.
Tell us what photo Editor you are using and maybe someone can tell you how to control the compression.
I only know Photoshop, but many in this NG have used every imaginable photo editor. They can surely help you.
Bob Williams

Of course I’m using Photoshop, this is a NG about Photoshop, isn’t it? Now I get a file from my digital camera, say org.jpg, size 599K, 1600×1200
pixels = about 2Mpixels, I enter Photoshop, open org.jpg and choose autolevels, then file – close, it asks me "Save the modifications?", I choose yes and I get org.jpg with size 375K I thought it must have expanded the file as a bitmap, applied auto level by scaling the 3 RGB bytes representing each pixel, then re-compressed the file at the same degreee as at beginning (it did not ask me the jpg compression level)
but why is the size about halved?
il barbi

After you do your Auto Levels operation.
Try the FILE >>> SAVE AS option and then select the highest quality. Check the number of pixels then.
Bob

saved the file with quality 12 – the pixels are still 1600×1200 and file size 1069K (!)
il barbi

"il barbi" wrote:

<snip>

After you do your Auto Levels operation.
Try the FILE >>> SAVE AS option and then select the highest quality. Check the number of pixels then.
Bob

saved the file with quality 12 – the pixels are still 1600×1200 and file size 1069K (!)
il barbi

And now it may be the best chance to ask and learn WHY the 1600×1200 doesn’t mean much. It seems like you *still* haven’t got the clue why 1600×1200 doesn’t mean much.

il barbi wrote:

"Bob Williams" ha scritto nel messaggio

il barbi wrote:

(I think
I’m puzzled with such operation: I apply auto levels to some jpgs from my digital camera (1600×1200 pixel), with file size about 600K, and I get file size about 300K!
Someone can explain?
il barbi

Your Photo Editing Program COMPRESSED your image more than it was originally.
In Photoshop, and probably others, you can choose the degree of compression you want in the SAVED image.
Tell us what photo Editor you are using and maybe someone can tell you how to control the compression.
I only know Photoshop, but many in this NG have used every imaginable photo editor. They can surely help you.
Bob Williams

Of course I’m using Photoshop, this is a NG about Photoshop, isn’t it? Now I get a file from my digital camera, say org.jpg, size 599K, 1600×1200 pixels = about 2Mpixels, I enter Photoshop, open org.jpg and choose autolevels, then file – close, it asks me "Save the modifications?", I choose yes and I get org.jpg with size 375K

You ignored the levels of compression available.

Joe wrote:

"il barbi" wrote:

<snip>

After you do your Auto Levels operation.
Try the FILE >>> SAVE AS option and then select the highest quality. Check the number of pixels then.
Bob

saved the file with quality 12 – the pixels are still 1600×1200 and file size 1069K (!)
il barbi

And now it may be the best chance to ask and learn WHY the 1600×1200 doesn’t mean much. It seems like you *still* haven’t got the clue why 1600×1200 doesn’t mean much.

Give it up. She is clueless. Even ‘lossless’ jpg compression creates smaller files.

Let her wallow.

il barbi wrote:

"Bob Williams" ha scritto nel messaggio

il barbi wrote:

"Bob Williams" ha scritto nel messaggio

il barbi wrote:

(I think
I’m puzzled with such operation: I apply auto levels to some jpgs from my digital camera (1600×1200 pixel), with file size about 600K, and I get file size about 300K!
Someone can explain?
il barbi

Your Photo Editing Program COMPRESSED your image more than it was originally.
In Photoshop, and probably others, you can choose the degree of compression you want in the SAVED image.
Tell us what photo Editor you are using and maybe someone can tell you how to control the compression.
I only know Photoshop, but many in this NG have used every imaginable photo editor. They can surely help you.
Bob Williams

Of course I’m using Photoshop, this is a NG about Photoshop, isn’t it? Now I get a file from my digital camera, say org.jpg, size 599K, 1600×1200
pixels = about 2Mpixels, I enter Photoshop, open org.jpg and choose autolevels, then file – close, it asks me "Save the modifications?", I choose yes and I get org.jpg with size 375K I thought it must have expanded the file as a bitmap, applied auto level by scaling the 3 RGB bytes representing each pixel, then re-compressed the file at the same degreee as at beginning (it did not ask me the jpg compression level)
but why is the size about halved?
il barbi

After you do your Auto Levels operation.
Try the FILE >>> SAVE AS option and then select the highest quality. Check the number of pixels then.
Bob

saved the file with quality 12 – the pixels are still 1600×1200 and file size 1069K (!)
il barbi

Yes! I misspoke.
The number of pixels does NOT change.
The number of kilobytes needed to describe the pixels does. That is what Compression is all about.
High Compression = Fewer kilobytes….Low Compression = More kilobytes If you want to get a feel for how compression affects the file size in kilobytes, take any picture from your camera, look at the file size. Do an Auto Levels or anything else and SAVE AS (give it a new name e.g. pic2.) and select the highest compression (Image quality = 0) Now just SAVE AS again. Call it pic3 and select the Lowest compression (Image Quality = 12)
Now compare the file size for each image…The differences in file size are huge. The number of pixels remains the same.
Bob

Bob Williams wrote:

After you do your Auto Levels operation.
Try the FILE >>> SAVE AS option and then select the highest quality. Check the number of pixels then.
Bob

saved the file with quality 12 – the pixels are still 1600×1200 and file size 1069K (!)
il barbi

Yes! I misspoke.
The number of pixels does NOT change.
The number of kilobytes needed to describe the pixels does. That is what Compression is all about.
High Compression = Fewer kilobytes….Low Compression = More kilobytes If you want to get a feel for how compression affects the file size in kilobytes, take any picture from your camera, look at the file size. Do an Auto Levels or anything else and SAVE AS (give it a new name e.g. pic2.) and select the highest compression (Image quality = 0) Now just SAVE AS again. Call it pic3 and select the Lowest compression (Image Quality = 12)
Now compare the file size for each image…The differences in file size are huge. The number of pixels remains the same.
Bob

As some of us have mentioned quite afew times before, besides the compression which is part of "quality" the resolution of the graphic requires minimum 3 main values to make a TRUE VALUE.

If we just look at the value 1600×1200 then

– 1600×1200 could be a complete value for VIDEO *not* not graphic

– 1600×1200 and *compression* is for the quality still *not* a *whole* VALUE of a graphic format.

– 1600×1200 x 1-PPI has lower value than 16×12 x 1000-PPI, or it’s only 1/10 of the 16x12x1000-PPI

"Bob Williams" ha scritto nel messaggio

il barbi wrote:

"Bob Williams" ha scritto nel messaggio

il barbi wrote:

"Bob Williams" ha scritto nel messaggio

il barbi wrote:

(I think
I’m puzzled with such operation: I apply auto levels to some jpgs from my digital camera (1600×1200 pixel), with file size about 600K, and I get file size about 300K!
Someone can explain?
il barbi

Your Photo Editing Program COMPRESSED your image more than it was originally.
In Photoshop, and probably others, you can choose the degree of compression you want in the SAVED image.
Tell us what photo Editor you are using and maybe someone can tell you how to control the compression.
I only know Photoshop, but many in this NG have used every imaginable photo editor. They can surely help you.
Bob Williams

Of course I’m using Photoshop, this is a NG about Photoshop, isn’t it? Now I get a file from my digital camera, say org.jpg, size 599K, 1600×1200
pixels = about 2Mpixels, I enter Photoshop, open org.jpg and choose autolevels, then file – close, it asks me "Save the modifications?", I choose yes and I get org.jpg with size 375K I thought it must have expanded the file as a bitmap, applied auto level by scaling the 3 RGB bytes representing each pixel, then re-compressed the file at the same degreee as at beginning (it did not ask me the jpg compression level)
but why is the size about halved?
il barbi

After you do your Auto Levels operation.
Try the FILE >>> SAVE AS option and then select the highest quality. Check the number of pixels then.
Bob

saved the file with quality 12 – the pixels are still 1600×1200 and file size 1069K (!)
il barbi

Yes! I misspoke.
The number of pixels does NOT change.
The number of kilobytes needed to describe the pixels does. That is what Compression is all about.
High Compression = Fewer kilobytes….Low Compression = More kilobytes If you want to get a feel for how compression affects the file size in kilobytes, take any picture from your camera, look at the file size. Do an Auto Levels or anything else and SAVE AS (give it a new name e.g. pic2.) and select the highest compression (Image quality = 0)
Now just SAVE AS again. Call it pic3 and select the Lowest compression (Image Quality = 12)
Now compare the file size for each image…The differences in file size are huge. The number of pixels remains the same.

I found where is the problem – I was using PS rel.6.0… You can verify, if you want, that after applying autolevels to org.jpg and closing the file, PS
6.0 does not ask what level of compression is to be chosen, in the contrary
PS 7.0 does. Moreover PS 6.0 assumes the current level of compression, which may vary between 1 and 12 depending on the last operation involving the request of this parameter. So by doing autolevels+close the result may vary very much. I don’t know if this is a bug of PS 6.0 or a problem of my PS installation, anyway it is better to pass away, I’ll use PS 7.0. Now my question arose from this problem: I want to apply autolevels to the jpg files from my Fuji digital camera (this is a compact one, no raw output). I don’t know what jpg algorithm Fuji applies to the 2Mpixel of each photo, I only know the photos occupy about 600K. Now since autolevel function only applies some scaling to each group of 3 bytes representing each pixel, I expect to get more or less the same memory size but I don’t want to add a further loss to the loss that Fuji has already caused. On the other side if I save the autoleveled file with maximum (12) degree I get a much greater filesize (1069K for the 599K file I quoted) and this seems nonsense
il barbi

"John Stafford" wrote in message

il barbi wrote:

"Bob Williams" ha scritto nel messaggio

il barbi wrote:

(I think
I’m puzzled with such operation: I apply auto levels to some jpgs from my digital camera (1600×1200 pixel), with file size about 600K, and I get file size about 300K!
Someone can explain?
il barbi

Your Photo Editing Program COMPRESSED your image more than it was originally.
In Photoshop, and probably others, you can choose the degree of compression you want in the SAVED image.
Tell us what photo Editor you are using and maybe someone can tell you how to control the compression.
I only know Photoshop, but many in this NG have used every imaginable photo editor. They can surely help you.
Bob Williams

Of course I’m using Photoshop, this is a NG about Photoshop, isn’t it? Now I get a file from my digital camera, say org.jpg, size 599K, 1600×1200
pixels = about 2Mpixels, I enter Photoshop, open org.jpg and choose autolevels, then file – close, it asks me "Save the modifications?", I choose yes and I get org.jpg with size 375K

You ignored the levels of compression available.

OK barbi once again

it is not the autolevel action that is changing your file but the CLOSE AND SAVE action

yes you can save at higher and lower compression that you can choose BUT you will still be compressing an already compressed file

you may not notice the degrading of image but it is there

for example let’s say you open the new file you made
it is a compressed copy of the orig
then you do some more processing
and again save as jpg
no matter what compression you choose now you have a compressed copy of an already compressed copy

do you get it?

"Kabuki" ha scritto nel messaggio

OK barbi once again
cut <
do you get it?

please see my text of aug.13, 22h49′
anyway suppose you have such jpg and want to apply autolevels and save, what would you do?
il barbi

On Fri, 14 Aug 2009 21:30:25 +0200, "il barbi" wrote:

"Kabuki" ha scritto nel messaggio

OK barbi once again
cut <
do you get it?

please see my text of aug.13, 22h49′
anyway suppose you have such jpg and want to apply autolevels and save, what would you do?
il barbi

Autolevels sound so unimaginative.
I almost never use it.
Granted, I never do batch

"il barbi" wrote:

"Kabuki" ha scritto nel messaggio

OK barbi once again
cut <
do you get it?

please see my text of aug.13, 22h49′
anyway suppose you have such jpg and want to apply autolevels and save, what would you do?
il barbi

The man asked "Do you get it?" which means "you haven’t got it".

– Do whatever you want to do as it doesn’t make much or any difference.

– Many people use LEVEL but most people don’t use autolevel.

– The man and other men keep reminding you about the "COMPRESSION" that is the part you haven’t got.

"il barbi" wrote in message

"Kabuki" ha scritto nel messaggio

OK barbi once again
cut <
do you get it?

please see my text of aug.13, 22h49′
anyway suppose you have such jpg and want to apply autolevels and save, what would you do?
il barbi

I use a different workflow (open in Bridge>use ACR>>make the batch adjustment.. Save as >tiff

and I very rarely use auto level
it is like using the camera to make the exposure and aperture decisions (auto settings)
I use curves if I am opened in PS- I resisted that for a long time until I learned it’s superiority

do you only have version 7?
I think it has no Bridge or jpgs can open as RAW?

"Kabuki" ha scritto nel messaggio

anyway suppose you have such jpg and want to apply autolevels and save, what would you do?
il barbi

I use a different workflow (open in Bridge>use ACR>>make the batch adjustment.. Save as >tiff

and I very rarely use auto level
it is like using the camera to make the exposure and aperture decisions (auto settings)
I use curves if I am opened in PS- I resisted that for a long time until I learned it’s superiority

now my problem is mainly for a peculiar job – I use to photograph old documents in a historical archive (ok it would be better to set some copy stand with 45

il barbi wrote:

"Bob Williams" ha scritto nel messaggio

il barbi wrote:

"Bob Williams" ha scritto nel messaggio

il barbi wrote:

"Bob Williams" ha scritto nel messaggio

il barbi wrote:

(I think
I’m puzzled with such operation: I apply auto levels to some jpgs from my digital camera (1600×1200 pixel), with file size about 600K, and I get file size about 300K!
Someone can explain?
il barbi

Your Photo Editing Program COMPRESSED your image more than it was originally.
In Photoshop, and probably others, you can choose the degree of compression you want in the SAVED image.
Tell us what photo Editor you are using and maybe someone can tell you how to control the compression.
I only know Photoshop, but many in this NG have used every imaginable photo editor. They can surely help you.
Bob Williams

Of course I’m using Photoshop, this is a NG about Photoshop, isn’t it? Now I get a file from my digital camera, say org.jpg, size 599K, 1600×1200
pixels = about 2Mpixels, I enter Photoshop, open org.jpg and choose autolevels, then file – close, it asks me "Save the modifications?", I choose yes and I get org.jpg with size 375K I thought it must have expanded the file as a bitmap, applied auto level by scaling the 3 RGB bytes representing each pixel, then re-compressed the file at the same degreee as at beginning (it did not ask me the jpg compression level)
but why is the size about halved?
il barbi

After you do your Auto Levels operation.
Try the FILE >>> SAVE AS option and then select the highest quality. Check the number of pixels then.
Bob

saved the file with quality 12 – the pixels are still 1600×1200 and file size 1069K (!)
il barbi

Yes! I misspoke.
The number of pixels does NOT change.
The number of kilobytes needed to describe the pixels does. That is what Compression is all about.
High Compression = Fewer kilobytes….Low Compression = More kilobytes If you want to get a feel for how compression affects the file size in kilobytes, take any picture from your camera, look at the file size. Do an Auto Levels or anything else and SAVE AS (give it a new name e.g. pic2.) and select the highest compression (Image quality = 0)
Now just SAVE AS again. Call it pic3 and select the Lowest compression (Image Quality = 12)
Now compare the file size for each image…The differences in file size are huge. The number of pixels remains the same.

I found where is the problem – I was using PS rel.6.0… You can verify, if you want, that after applying autolevels to org.jpg and closing the file, PS
6.0 does not ask what level of compression is to be chosen, in the contrary
PS 7.0 does. Moreover PS 6.0 assumes the current level of compression, which may vary between 1 and 12 depending on the last operation involving the request of this parameter. So by doing autolevels+close the result may vary very much. I don’t know if this is a bug of PS 6.0 or a problem of my PS installation, anyway it is better to pass away, I’ll use PS 7.0. Now my question arose from this problem: I want to apply autolevels to the jpg files from my Fuji digital camera (this is a compact one, no raw output). I don’t know what jpg algorithm Fuji applies to the 2Mpixel of each photo, I only know the photos occupy about 600K. Now since autolevel function only applies some scaling to each group of 3 bytes representing each pixel, I expect to get more or less the same memory size but I don’t want to add a further loss to the loss that Fuji has already caused. On the other side if I save the autoleveled file with maximum (12) degree I get a much greater filesize (1069K for the 599K file I quoted) and this seems nonsense
il barbi

Since your Fuji outputs a 2MP image, and it takes 3 bytes (RGB) to describe a pixel, a totally uncompressed file would be 6 megabytes. But your camera compresses the image to 600 KB. So Fuji’s algorithm uses ABOUT a 10:1 compression. (Actual compression ratio depends on the image content). 10:1 is a pretty high compression ratio. Perhaps you are NOT using the Finest Quality setting on your camera.
Most P/S cameras offer 3 degrees of user-selectable quality. Something like Super Fine….Fine….Normal or similar.
Choose the Finest Quality your camera offers
You MAY see an improvement in image quality if you make 8×10 enlargements. Probably no visible difference at 4×6.
Bob Williams

"Bob Williams" ha scritto nel messaggio

Since your Fuji outputs a 2MP image, and it takes 3 bytes (RGB) to describe a pixel, a totally uncompressed file would be 6 megabytes. But your camera compresses the image to 600 KB. So Fuji’s algorithm uses ABOUT a 10:1 compression. (Actual compression ratio depends on the image content). 10:1 is a pretty high compression ratio. Perhaps you are NOT using the Finest Quality setting on your camera.

ok I’m not using the finest quality, this is only allowed with 12Mpixels and results in files of 6 MBytes, with a compression ratio of about 6:1. There is also the "normal" quality with 12Mpixels, leading to 3MB files (compression ratio 12:1). But my problem is not to achieve maximum quality, as I hope to made it understand (apart of my poor english language). I’m just satisfied with 2Mpixels in a peculiar task of photographing old documents, as I tell in another branch of this thread, with jpg size 600K. The original problem I told at the beginning was due to some bad behaviour of PS 6.0 leading to 300K jpgs with further loss of data. Now the problem is to improve the 600K resulting jpgs, since they are too dark, hopefully without further loss of data and memory increasing
il barbi

On Sun, 16 Aug 2009 13:40:31 +0200, il barbi wrote:

"Bob Williams" ha scritto nel messaggio

Since your Fuji outputs a 2MP image, and it takes 3 bytes (RGB) to describe a pixel, a totally uncompressed file would be 6 megabytes. But your camera compresses the image to 600 KB. So Fuji’s algorithm uses ABOUT a 10:1 compression. (Actual compression ratio depends on the image content). 10:1 is a pretty high compression ratio. Perhaps you are NOT using the Finest Quality setting on your camera.

ok I’m not using the finest quality, this is only allowed with 12Mpixels and results in files of 6 MBytes, with a compression ratio of about 6:1. There is also the "normal" quality with 12Mpixels, leading to 3MB files (compression ratio 12:1). But my problem is not to achieve maximum quality, as I hope to made it understand (apart of my poor english language). I’m just satisfied with 2Mpixels in a peculiar task of photographing old documents, as I tell in another branch of this thread, with jpg size 600K. The original problem I told at the beginning was due to some bad behaviour of PS 6.0 leading to 300K jpgs with further loss of data. Now the problem is to improve the 600K resulting jpgs, since they are too dark, hopefully without further loss of data and memory increasing
il barbi

This does not sound difficult at all. Put one of the images up on flickr.com, or a similar service, and we’ll see what we can do.

Your English is excellent, BTW.
—
Mike Russell – http://www.curvemeister.com

"Mike Russell" ha scritto nel messaggio

Now the problem is
to improve the 600K resulting jpgs, since they are too dark, hopefully without further loss of data and memory increasing
il barbi

This does not sound difficult at all. Put one of the images up on flickr.com, or a similar service, and we’ll see what we can do.

thank you, this is the link:
http://rapidshare.de/files/48133071/DSCF2763.jpg.html
this file has 1600×1200 pixels and size 599K, I must rotate it clockwise and lighten (I use to apply autolevels)
anyway after going into this thread I realize I’m wrong when speaking of memory occupation, indeed I only must try to minimize it on my HD but not necessarily in my Fuji – it has a 2GB memory card, I could as well shoot at 4Mpixels (.jpg size 1,2MB -> about 1600 photos) and then apply some lossy operations and get anyway a good result
il barbi

On Sun, 16 Aug 2009 21:47:26 +0200, il barbi wrote:

"Mike Russell" ha scritto nel messaggio

Now the problem is
to improve the 600K resulting jpgs, since they are too dark, hopefully without further loss of data and memory increasing
il barbi

This does not sound difficult at all. Put one of the images up on flickr.com, or a similar service, and we’ll see what we can do.

thank you, this is the link:
http://rapidshare.de/files/48133071/DSCF2763.jpg.html

The upload site is … challenging. I did a screen capture and saved that as a jpeg at normal quality, for a file fize of 151 Kbytes. So there’s some savings for you already, LOL.

I did a number of experiments – I got the best appearance by using Levels (curves actually, LOL) to get the handwriting as close to black on white as possible, while retaining the form of the letters and eliminating the writing from the reverse side of the page. I selected the green channel, and saved that as a jpeg at 50% quality. The resulting file was somewhat larger, about 151 Kbytes.

For a second experiment, I did a Save for Web and saved a 4 level GIF file – this got the size down to 32Kb, with the handwriting clearly legible as black against white.

Unfortunately, the web site I use for displaying images is misbehaving – I’ll follow up later with some examples. It does seem to be the case that you can apply an action to your images, and save them as grayscale jpeg’s and still retain the quality you need to read the writing. I would recommend that you archive your original images to a DvD for safekeeping in any case.

I highly recommend flickr as a place to upload your images. It’s free, and does not require extra effort for people who want to download your images. —
Mike Russell – http://www.curvemeister.com

il barbi wrote:

"Kabuki" ha scritto nel messaggio

anyway suppose you have such jpg and want to apply autolevels and save, what would you do?
il barbi

I use a different workflow (open in Bridge>use ACR>>make the batch adjustment.. Save as >tiff

and I very rarely use auto level
it is like using the camera to make the exposure and aperture decisions (auto settings)
I use curves if I am opened in PS- I resisted that for a long time until I learned it’s superiority

now my problem is mainly for a peculiar job – I use to photograph old documents in a historical archive (ok it would be better to set some copy stand with 45° lights and tripod but it is not allowed), I set my Fuji F100fd to shooting mode "museum" (no flash, no beep), 2Mpixel are enough for a single page, I get jpg files sized about 600K with good resolution but too dark, so I used to postprocess them with such batch: "rotate 90° right – autolevels – save" and I noticed that the size became about a half (300K). As I said, this was a problem of PS 6.0 and I understand I must specify the degree of jpg compression and that this will introduce a new loss in data. I understand most people in this thread blame using jpgs and support lossless formats but I must also take care of disk occupation, 600K is a tolerable size for just one page. Now I’d like to make my photos lighter without memory increasing and further loss of data. If I apply autolevels, or any other lightening operation, and save as tiff or even jpg-12 I get much greater sizes…
il barbi

If you just want to make the picture lighter without using AUTO LEVELS in post processing, just set the exposure compensation to produce a lighter image……….OR…….
See what aperture and speed your camera is using in Auto Mode. Then set your camera on manual and choose a larger aperture at the same speed.
Bob Williams