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high res --low res did not know this

Started by milanab, December 11, 2006, 09:06:33 AM

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if you look at your images in the 12.5%, 25%.50% 75% or 100% they are high res.  If you look at them, as i often have at 33% or 66% they are low res and therefore you see jagged edges etc.  i tried it with two of my images this morning and i was amazed.  this may only apply to doing certain types of images but i think i have thrown out some i would have kept had i known this.
without faith...there is no hope


Oh yea, I saw a clip about that the other day, when viewing an image at the different %'s the resolution varies. Think it has something to do with saving time or 'puter resources for a complete redraw of the image.


It really has more to do with how the image pixels line up with your monitor's pixels.  At "odd" magnifications, aliasing effects can make an image appear pixellated, jagged, or just less sharp when the image information is shared across screen pixels.  At "even" magnifications, the image pixels are the same as, or even multiples of your monitor's pixels, so the image looks smooth.  This is why I usually work in the zoom levels you mentioned above (12.5%, 25%, 50%, 100%) or at 150%, 200% ... etc.




I tend to think there may be other factors at play here also, I have also noticed that viewing large image files in PS at screen size the image quality is degraded yet when you view the same image in the Windows Fax and Image Viewer the image displays OK at all sizes, unless you blow it out till it pixellates, it could be the way different programs interpolates the file.

Wisdom is having a well considered opinion .... and being smart enough to keep it to yourself!     MJS

"Life" is what happens while you are planning other things!



You are absolutely right about how images are displayed in Windows Picture and Fax viewer.  It interpolates the image to make it look smooth regardless of zoom level.  Photoshop doesn't do this so that you can zoom and pan faster, but also because it isn't "true" to the actual image.  If Photoshop interpolated it's display the way Windows Picture and Fax viewer does and you zoomed in above 100%, it would blur the image and you wouldn't see the pixels accurately.