RDKirk wrote:
I wouldn\'t call it \"pixel peeping,\" but for sure unless physically restrained, viewing audiences will get as close to a photograph as possible--up to reading distance--regardless of the size of the image.
The limiting factor is the resolving power of the eye. It can resolve fine detail at reading distance, but as viewing distance increases the fine detail will blur together and seem flat compared with an image with less detail but more contrast.
So notwithstanding the inclination of people to get up close and pixel peep they can only see the entire image from a greater distance and as the viewing distance increases it is necessary to change the contrast and resolution of the image to maintain the same overall perceptual effect.
Painters realized that fact long ago. One of my favorite painters is John Singer Sargent who did larger than life portraits which have stunning clarity and detail when viewed from across the room. But up close at the gallery you find he actually applied most of the paint with broad strokes of palette knife and the sharpness was created with the very clever use of contrasting highlights much in the way unsharp masking creates the illusion of increased sharpness in a digital image.
The optimal situation is to have enough capture resolution to make up-sampling unnecessary. My first 2.1 MP digital, did good job with a 4 x6 print at 300 ppi. My 5MP Minolta D7Hi produced a decent 5x7. My 20D a comparable 8x10. But when I first got my DC290 I did some experimenting making a 24 x 30 print two different ways. First I kept the file size the same pixel dimensions and lowered output resolution. For comparison I rescaled the image by resampling to the same 300ppi resolution. Its a big like a bargain with the devil in that neither produced an optimal result, but I found that the preserving the original file detail, plus optimal sharpening, produced a better looking image perceptually than the resampled version. LIke the Singer paintings the one with the \"bigger dots\" with more contrast fooled my eye into thinking it was sharper. Sharpening the resampled file didn\'t have the same effect because the resampling had diluted the original image detail. Its an interesting experiment which shows the role human perception plays in the process. Try it some time
Now when I edit a photo I save an unsharpened, un-cropped version as a TIFF as the \"master\" then open, crop and resize before sharpening. The bigger the print, the more USM I apply to maintain the same perceptual image quality. Up close a large print will look over-sharpened but if you was to hold a 4x6 copy at reading distance and then look at the 11x14 with higher USM from several feet away they look about the same perceptually.
Chuck
Nov 05, 2008 at 07:36 PM
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