resizing question

Viv writes …

would a specialist program like Genuine Fractals or
S-Spline give noticeably better results than simply resizing them in Photoshop (mine is Photoshop 6) using bicubic interpolation? And if using PS6, is it best to just resize in one jump or in small increments?

Here’s an example comparing the "small increments" method (commonly known as ‘stair interpolation’) to several other methods, about the time of Photoshop 6 … http://www.fredmiranda.com/SI/ …

wrote in message

I need to increase the size of some images I already have on disc (can’t re-scan them as originals are lost). I may have to double the file size, which is quite an increase.

My question is: would a specialist program like Genuine Fractals or S-Spline give noticeably better results than simply resizing them in Photoshop (mine is Photoshop 6) using bicubic interpolation? I’m asking this because I really don’t want to go to the expense of one of these programs if I can avoid it.

And if using PS6, is it best to just resize in one jump or in small increments?

Thanks in advance

Viv

Make your own action for it.

Open an image you want res up.

Open the Actions palette and select "New Set".

Name it "Creeping Increase" or whatever you like.

Now select New Action and call it "1.5 Increase"

Next go to Image/Size and put a check in "Resample" and "Constrain Proportions"

with Bicubic and change the width drop down to "percent" and enter 110.

Now go to "Image Size" do the same 3 more times.

Then "Stop Recording"

Next "New Action" Name it "2.0 Increase"

Now "Edit/Purge All"

Next select the "1.5 Increase" in the Actions Palette

and press the Play button.

select the "1.5 Increase" again,

press the Play button again.

Stop Recording.

"New Action" Name it 3.0 Increase.

"Edit/Purge All"

Select and play the "2.0 Increase"

Select and play the "1.5 Increase"

Stop Recording.

"New Action" Name it 4.0 Increase.

"Edit/Purge All"

Select and play the "3.0 Increase"

Now "Image Size" 110 percent.

And again "Image Size" 110 percent.

Stop Recording.

Save the Action.

Hello. I’m Stupid. So tell me about this iterative upsampling method.

Why would one upsample in 10% iterations rather than a specific percentage of the image size with each step, thereby changing the % interation with each step? What stays constant (or remains insignficant) about the bit-pattern that makes 10% work?

Or are folks just making intuitive guesses, hoping for the best, or possibly thinking that somehow they are stealthily creeping up on the laws of nature so she doesn’t notice?

On Tue, 20 Dec 2005 08:16:24 -0600, "Lorem Ipsum" wrote:

Hello. I’m Stupid. So tell me about this iterative upsampling method.
Why would one upsample in 10% iterations rather than a specific percentage of the image size with each step, thereby changing the % interation with each step? What stays constant (or remains insignficant) about the bit-pattern that makes 10% work?

Or are folks just making intuitive guesses, hoping for the best, or possibly thinking that somehow they are stealthily creeping up on the laws of nature so she doesn’t notice?

This method has been around quite a while. As far as I know, it is empirical in origin. Someone tried it and found that the observed result was better than a single up-sampling. Sounds a bit like "snake oil" to me, too, but I have tried it, and, to my eye, it produces slightly better results than the single up-sampling approach.

I also think that GF produces still better results. The difference is noticable to me in a side-by-side comparison, but it is not miraculous — just a bit better. GF and its ilk provide alternative up-sampling algorithms to the built-in ones.

These methods are still trying to "guess" what the missing pixels should be. It takes some experimentation to see what produces the most pleasing results for you.

Leonard

"Lorem Ipsum" wrote in message

Hello. I’m Stupid. So tell me about this iterative upsampling method.
Why would one upsample in 10% iterations rather than a specific percentage of the image size with each step, thereby changing the % interation with each step? What stays constant (or remains insignficant) about the bit-pattern that makes 10% work?

Or are folks just making intuitive guesses, hoping for the best, or

possibly

thinking that somehow they are stealthily creeping up on the laws of

nature

so she doesn’t notice?

Thank goodness – I’m glad I’m not the only one who thinks like that. To me, it’s like suggesting that it is more accurate to measure a distance of 10 metres using a 30cm ruler rather than a surveyor’s tape. However, how do you explain the comparisons in Bill Hilton’s link? I can’t think of any scientific explanation.

I know the OP is using Photoshop 6, but does anyone know how Photoshop CS ‘Bicubic Smoother’ differs from ‘Bicubic’? This is usually recommended for upsampling, and IME produces fewer artifacts than straight bicubic.

—
John
Replace ‘nospam’ with ‘todnet’ when replying.

Lorem Ipsum writes …

Hello. I’m Stupid.

That explains a lot of your posts …

So tell me about this iterative upsampling method. Why would one upsample in 10% iterations rather than a specific percentage of the image size with each step, thereby changing the % interation with each step?

The search for the Magic Formula of Resizing was a bigger topic a few years back than it is now and people tried all sorts of things, like 1%, 2%, 5%, 10%, 50% and varying the % between 25/33/50 in steps (and of course doing it in one big jump). It’s easy to just write an Action for each of these (if you’re not Stupid) and run them and compare the results. For whatever reason 10% steps seemed to give the best results on the highest % of images in an acceptable amount of time.

The original poster was asking for a cheap way to resize using Photoshop 6 (which doesn’t have ‘bicubic smoother’) and the Miranda link shows comparisons of various methods for doing this, some better and cheaper than others. If you have a better suggestion then why don’t you provide it?

Or are folks just making intuitive guesses, hoping for the best, or possibly thinking that somehow they are stealthily creeping up on the laws of nature so she doesn’t notice?

It’s easy enough to run tests and compare results, unless of course you’re too Stupid 🙂

Bill

"Bill Hilton" wrote in message

Lorem Ipsum writes …

Hello. I’m Stupid.

That explains a lot of your posts …

Ah, at long last, recognition.

[…] It’s easy to just write an Action for each of these (if you’re not Stupid)

Now look here, I can cut Actions and Droplets, script and code very well (and you should know that), but I don’t believe that discredits my status as Stupid; I’ve worked long and hard for it and you can’t take it away. I am stupid!

and run them and compare the
results. For whatever reason 10% steps seemed to give the best results on the highest % of images in an acceptable amount of time.

How fortuitous that an even 10% works; a concordance of physics, or is it just the median of the Bell Curve? Or both?

[…] If you have a better suggestion then why don’t you provide it?

What? And give away my intellectual currency?

It’s easy enough to run tests and compare results, unless of course you’re too Stupid 🙂

I am afraid I am low-resolution impaired. I work in larger formats. But given that smarter people than I have worked long and hard at this (without even seeing Adobe’s code), and intuited the best that can be done and even made a living at selling solutions, I shall lay back in my aura of blissfull stupidity doing better.

—
Stupid