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I found there are 2 ways to change the image size in GIMP.

One is "Zoom", another is "Scale".

What is the difference of the 2 ways?

I do see some difference when I zoom (or scale) a TIFF to 600%. The result of zoom is more clear than scale.

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migrated from stackoverflow.com Jun 18 '10 at 5:10

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up vote 7 down vote accepted

Zoom does not change image size, it affects only how it is presented on screen. It;s like magnification. Scale changes physical image size.

For example, imagine you have 256x256 pixels image. If you zoom it to 50%, image will still be 256x256 pixels, although on screen it will take 128x128 pixels. When you scale that image to 50%, its size will be 128x128 pixels.

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Thank you. I understand it now. But do you know why the quality is difference even in the same level? As I said above, I zoom a TIFF to 600%, and scale the same TIFF to 600%, the quality of zoom is more clear. The scaled image is kind of fuzzy. Thanks. – Landy Jun 11 '10 at 0:58
1  
Are you sure you don't have that backwards? There are multiple algorithms - some are more 'fast' and others are more 'accurate'. You'd want to use a 'fast' algorithm for zoom (since it's happening in response to a user event) and an 'accurate' one for scale (as this would produce a permanant change to the image). There may be other issues as well though - perhaps your scale operation isn't preserving the image's aspect ratio or something else. – Nate Jun 17 '10 at 22:54
    
@el pescado:Sorry for accepting your answer to late. I just know I should do it after I get a right answer. :) – Landy Apr 21 '11 at 9:02
    
@Nate, thank you:) – Landy Apr 21 '11 at 9:03

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