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Old Jul 17, 2006, 12:07 AM   #1
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Can someone help me..

I need an iterpolation program or a method to interpolate with photoshop CS

Thanks alot

Boily
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Old Jul 18, 2006, 11:36 AM   #2
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You may want to give more details on what you're trying to accomplish (starting resolution, desired print size, if you're using a service or will be printing yourself, etc).

I've moved this thread to our Resizing and Interpolation Forum (since we have a forum dedicated to these types of questions).

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Old Jul 18, 2006, 2:22 PM   #3
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I like stepped interpolation (SI) in 5% increments. I also have the Genuine Fractals 4 plug-in. According to the subject I sometimes prefer one over the other, but SI is good since it is free.

Start an action and increase your pixels by 5%. Do that 5 times and finish the action. I name it 5 X 5%. Start another action and run the first action 4 times. I name it 4 X 25% even though that isn't really accurate – I just need to know what it is. Between the two actions you can come pretty close to a desired size. If you are shooting for an 13 X 19 at 300 PPI there isn't any reason to hit it exactly. The print spooler is going to readjust the pixels anyway. And if you are having it printed commercially they will discard any pixels they can't use. Some commercial sites recommend you don't upsample because they feel they can do it better.

Some people use 2% increases and others 10%. Which you choose has a lot to do with how much RAM and patience you have. 10% is faster and there isn't a lot of difference. 2% is a little better but really slow unless you have a fast computer and lots of RAM. I use SI only for upsamples and use Genuine Fractals for reducing the image size. Bicubic sharper probably works as well for a downsample.

I had seen reference to a technique of using a 120% increase with bicubic smoother and then reducing to the target size with bicubic sharper. It didn't do much, but as is often the case there is more to it. You might read through this and see if it suits you: http://www.outbackphoto.com/workflow/wf_60/essay.html The linked plug-in doesn't seem to be available.

Many people like Qimage for the resample filters. I tried it a long time ago when Lanczos was their best resample filter and wasn't impressed. But they have evidently improved it quite a bit over that older version. Steve has a separate Qimage forum and the developer participates. You might ask whether anyone has done comparisons with programs like Genuine Fractals.

Sharpen after you upsample. I set my camera sharpening to low so it doesn't get involved with all the post processing. You might read some good sharpening tutorials.

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Old Jul 18, 2006, 10:41 PM   #4
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Thanks alot for the information :-)
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