"Norm Dresner" wrote in message
[re Photoshop preview resampling inaccuracies]
Absolutely! I zoomed in on a very small area and then flattened the image
and there was absolutely no difference in the pixels I could see at that level. I suppose I should have guessed this when a previous experiment showed that the effect was dependent on the size of the image — doing the same thing with a very small image produced no effect.
There are a number of effects that preview differently, depending on the zoom. These are fairly rare, though, so it’s not unusual for people to be surprised when it happens.
SO … Let’s see … The images that Photoshop presents on the screen are all approximate because they have to be sampled at the screen resolution —
which in my case is 1920×1440 or about 128 PPI. But when I print, the resolution is (usually) 300 PPI. Does that mean that I can zoom to, say, 3x
the Fit-On-Screen magnification and see what the actual pixels that will be
laid down on the paper would look like? Your 100% recommendation is ~4.5x
the F-O-S magnification of 22.5%.
My recommendation would be to flatten the image temporarily, then set the zoom to match the print size.
When you view a zoomed out preview, Photoshop saves time by resampling first, then flattening. When you print, Photoshop does it in the opposite order: flattens first, then resamples to the resolution required by the printer driver.
For most images, this makes no earthly difference. A layer with a dithered bitmap image is a common case where this can matter. As a practical matter, if the appearance is not what you expect, 100% zoom is the most accurate preview. If you don’t want to zoom to 100 percent, flattening the image also gets a better preview.
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Mike Russell – www.curvemeister.com