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I have Psd image which is now 48x48 pixel and i like to change it to 128x128 without losing quality/resolution. How?

notes, the psd has multi layers

thank you.

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migrated from stackoverflow.com Jul 19 '10 at 15:13

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2 Answers 2

The question will be migrated to superuser.com soon. For the meantime:

It is not possible to enlarge a bitmap image without loss of quality. The data simply is not there. It's different from vector images where the image consists of geometric objects that can be enlarged indefinitely.

Photoshop's "Resize" dialog offers several interpolation filters with various results in quality. You can play around with them, but you will always suffer some loss in quality.

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Well, technically you're not losing quality, though you're not gaining any either ;-) –  Joey Jul 18 '10 at 10:52
    
well i guess so. anyhow i think my question is answered by now. Thank you guys for the input. –  Power-Mosfet Jul 18 '10 at 11:02

I'd say your best bet is to either to a normal resize and redraw the areas that are problematic or re-draw the entire image at the resolution you need. For bitmap images you can't put data where none existed before so resizing a 48 × 48 image to 128 × 128 won't look that good, naturally.

Icons are often drawn in vector graphics programs such as Illustrator and only exported to bitmaps. That way you retain all detail at multiple resolutions.

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Small icons (especially detailed ones) fare poorly when drawn in illustrator, even with CS5's pixel-grid. The vector interpolations simply can't accommodate the pixel interpretations, so lines get blurry and small objects may disappear entirely. –  Robusto Jul 18 '10 at 12:53
    
@Robusto: Yes, very small versions are often re-drawn as bitmaps again. However, both 48×48 and 128×128 aren't actually small icons anymore. –  Joey Jul 18 '10 at 21:55
    
@Johannes Rössel: This is hair-splitting. At that size they're not really icons, either, since their use as such is very limited. Most of the icons you're likely to find on most of the web pages in the world are probably in the neighborhood of 16x16. If the OP's question regards what's the best resampling method to use for resizing in PSD, then the answer is bicubic. –  Robusto Jul 19 '10 at 0:31
    
@Robusto: Maybe, yes. However, both 48×48 are icon sizes common in Windows so I didn't assume web pages initially. –  Joey Jul 19 '10 at 7:44

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