Increase Resolution!

[Diapositivo]

In principle one could you deconvolution methods to restore part of the high frequency part of the image, and this would give a true increase in resolution. However, I don't know if anyone is doing this.

In my recently-died machine, with Windows XP SP3, I had a Photoshop plug-in, Focus Magic, which did exactly this, it used deconvolution to try to extract some more resolution from the image. In my opinion, it helped a bit. My main motivation was not the resolution in itself, but the maniacal attitude of my agency's inspectors (Alamy, infamous for this) who would inspect images at 100% (mapped pixel to pixel to the monitor) to check sharpness. At that magnification the concept of "sharpness" becomes quite debateable and sometimes the inspector would reject an image (which means, for Alamy rules, an entire batch and sometimes a 30-day waiting period before a new upload) with the dreaded "soft or lacking definition" motivation.

That made me a bit paranoid about this aspect of photographic quality, and Focus Magic did give some help to the perception of sharpness at 100% magnification. I suppose the difference would have been totally unnoticeable in normal prints.

Photoshop itself (of which I was using a very old version, something like CS2 or CS3) had a checkbox in the sharpening dialog window which, even if not explicitly stated, would make some deconvolution.

 

[Prof_Pixel]

In my recently-died machine, with Windows XP SP3, I had a Photoshop plug-in, Focus Magic, which did exactly this, it used deconvolution to try to extract some more resolution from the image. In my opinion, it helped a bit. My main motivation was not the resolution in itself, but the maniacal attitude of my agency's inspectors (Alamy, infamous for this) who would inspect images at 100% (mapped pixel to pixel to the monitor) to check sharpness. At that magnification the concept of "sharpness" becomes quite debateable and sometimes the inspector would reject an image (which means, for Alamy rules, an entire batch and sometimes a 30-day waiting period before a new upload) with the dreaded "soft or lacking definition" motivation.

That made me a bit paranoid about this aspect of photographic quality, and Focus Magic did give some help to the perception of sharpness at 100% magnification. I suppose the difference would have been totally unnoticeable in normal prints.

Photoshop itself (of which I was using a very old version, something like CS2 or CS3) had a checkbox in the sharpening dialog window which, even if not explicitly stated, would make some deconvolution.

Please keep in mind that resolution and sharpness are NOT the same. Resolution is something that can be measured (in terms like MTF), while sharpness is a visual response. Using Unsharp Masking filtering to increase the contrast of edges gives the image more 'snap', but USM can not add any missing high frequency detail.

 

[Diapositivo]

Please keep in mind that resolution and sharpness are NOT the same. Resolution is something that can be measured (in terms like MTF), while sharpness is a visual response. Using Unsharp Masking filtering to increase the contrast of edges gives the image more 'snap', but USM can not add any missing high frequency detail.

I agree. I almost don't use unsharp-mask filtering at all, that's something which is left to the final user. I said that in Photoshop there is a check mark, in the unsharp-mask dialogue window which, if ticked, makes a deconvolution on the image.
When one observes any image at 100% magnification one does not really say "sharpness", a sharp image. A 4000 ppi scan of film, at 100% magnification, does not look "sharp".

I should have said that deconvolution helps a bit in transmitting a sense of sharpness to the image, if seen at 100%. But that evaluation by the inspector is, as you say, a "visual response", it's very subjective. A very little tiny bit of unsharp masking ("capture sharpening") and some deconvolution help in having my images pass the Alamy quality check, IMH experience.

 

[braxus]

Why not just shoot with a zoomed in lens, take several snaps of the image area you want, and then just stitch them together in software? You'd end up with more rez that way.

 

[nicodeal]

Speaking of the Nyquist limit - most/all digital cameras incorporate a low pass filter that removes high frequency information to avoid Nyquist aliasing effects and thus, throws away the 'very high sharpness' information.