Quote:

Quote:

Resizing a rasterized layer multiple times in a PSD will destroy its image quality.
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Myth or fact?

Common sense.

What you are probably really asking, is does checking the resample image box harm image quality.

The answer is that the resample image feature will either delete pixels (smaller image) or invent new ones (larger image), either of which dilutes the original image.

I think he's already aware of this. The question is... what happens if you do it multiple times?

For example, suppose I transform the image size, and resample it. Then I decide, "oh, that was just a little too small, so let me make it bigger," and transform the image size, resampling again.

Does Photoshop re-resize that image from the original size, or does it re-resize it from the resized image? The answer to that question, unfortunately, isn't common-sense. Common-sense would say "Photoshop knows the original image, and knows this is a scaled version of it -- even though just scaled a scaled version, so it should resize it from the original."

ImageMagick's "display" operates like this -- you can resize an image all you like, but it's not until you actually hit the "apply" button, does it discard the original, and start working from the resampled image. Any other operations you make before hitting the "apply" button are actually being done to the original sized image, which is apparent from the length of time it takes to run a filter on the image, compared to running a filter on an truly scaled image.

What would be nice is if you could build up a stack of image edits, or operations, that you've done to a resized image -- so you can get the speed, and then, once you're ready, apply that stack of image edits to the original image. The inability to do this is why Photoshop is an inappropriate tool for photography, and the reason for products like Lightroom. Photoshop could use some cross-pollination of the ideas, though, but hey... as hybrid8 pointed out, it's a legacy app.