Pyocat-HD/-MC 2 Bath Developing...

[Bob McCarthy]

What it did do was rekindle a lost aquaintance with D23. Found I can use it very effectively with TMY-2 (1:1) and it produces very nice negatives.

As you say it is not a divided developer. I got to this point adjusting time in bath (1) to match contrast range - left bath (b) alone at 4 min. In the end for wide dr scenes, it was a simplified 4 min in (a) and 4 min in (B). For normal, I just use D23 1:1.

bob

[Wally]

Perhaps I am not understanding the problem. However, in my experience if you start with 255 tones in your scan and do not clip highlight or shadow tonality you should still have 255 tones when you increase the contrast of an image file with the curves adjustment. I have adjusted the contrasty of many image files of scans of very flat negatives without losing tonal values and without causing posterization. It is obviously important to work with 16 bit files (or change your 8 bit file to 16 bit) but expanding of compressing contrast should not reduce the number of total tones that you have unless you clip at the top or at at bottom.

Sandy

I'm not understanding his problem or your response. It's probably me.

If he's only got 255 levels, his scanner is set to output 8-bit tiff files, I assume.

If that's the case, then if his image is of low contrast, his file only has values from, say, 90-170. Stretching these out to 5-250 (in curves or levels or anything) will not give him the smooth transitions between each discrete value he would have if his image originally had the info over the entire 0-255 tonal scale. Does PS actually interpolate the values in-between and smooth the image's tonal range? It would seem that might soften what should otherwise be hard transitions that were in the original subject and make things look smeared.

But your answer makes me wonder what's wrong with my thinking: I'd have suggested he tell his scan software to output 16-bit tiffs so he still has a smooth tonal range even after stretching out a compressed one.

Where is my thinking flawed?

[Bob McCarthy]

[QUOTE=Wally;637951]I'm not understanding his problem or your response. It's probably me.

If he's only got 255 levels, his scanner is set to output 8-bit tiff files, I assume.

Does PS actually interpolate the values in-between and smooth the image's tonal range? [QUOTE]



PS does not interpolate, otherwise we'd have an infinite set of levels again.

But, I believe a levels adjustment just moves original data range into a new 0-255 value range and therefore reassigns the original values to the new ones.

Still the potential for harshness/funkyness is there.

bob

[sanking]

PS does not interpolate, otherwise we'd have an infinite set of levels again.

But, I believe a levels adjustment just moves original data range into a new 0-255 value range and therefore reassigns the original values to the new ones.

Still the potential for harshness/funkyness is there.

bob

But if you only have 255 tonal values to begin with, as with an 8 bit scan, you should have 255 tones whether you scanned a normal contrast negative in PS and left it as is, or scanned a flat negative in PS and expanded the contrast with curves (with no clipping of highlight or shadow tonal values), or if you scanned a high contrast negative and compressed the contrast with curves. In all three cases you should still have 255 tones.

It is of course fairly easy to cause posterization when applying tonal corrections to 8 bit files, which is why we should either scan in 16 bit, or change our 8 bit files to 16 bit before making any tonal corrections.

Sandy

[sanking]

For scenes of extreme contrast, DD-23 doesn't produce "miracles" either, while Divided Pyrocat does.

For sheet film however, I like DD-23 for scenes of low to moderate contrast. Because development takes place in both solutions, you can use DD-23 to control contrast, while still getting some "extra" compensation afforded by the fact that developer gets extinguished in the highlights. Unlike other approaches, you can develop first for the high values in Solution A, and then for the shadows in Solution B. It gives full film speed and excellent shadow separation.

After restoring my membership in View Camera the other day, the first thing I did was download and read Sandy's article on DD-23 and Diafine - written, I presume, before his work with Divided Pyrocat.

Ken,

At the time I wrote the article on two bath development for View Camera I was already experimenting with two bath Pyrocat but for several reasons I chose not to include tests with Pyrocat in the article.

I agree with you that divided D23 is a good developer for scenes of moderate contrast, and of course if you used development by inspection with IR light you can control the final contrast by repeating the procedure in Solutions A and B until you get what you want. Of course, you could do the same thing in two bath Pyrocat if for some reason you needed to do so.

Sandy

[Ken Lee]

So far, while using DD-23, I haven't tried returning the film to Solution A - I have simply kept it in Solution A longer or shorter, to taste.

But your post reminds me that we can do this with Divided Pyrocat too - which is something worth experimenting with.

[Bob McCarthy]

But if you only have 255 tonal values to begin with, as with an 8 bit scan, you should have 255 tones whether you scanned a normal contrast negative in PS and left it as is, or scanned a flat negative in PS and expanded the contrast with curves (with no clipping of highlight or shadow tonal values), or if you scanned a high contrast negative and compressed the contrast with curves. In all three cases you should still have 255 tones.

It is of course fairly easy to cause posterization when applying tonal corrections to 8 bit files, which is why we should either scan in 16 bit, or change our 8 bit files to 16 bit before making any tonal corrections.

Sandy

But 0 to 255 assumes a range from pure white to pure black. If you have a flat neg/pos with neither, you would have to have some quantity less than 256 tones.

When you adjust levels so you have a white and a black then you by defination have all 256 tones.
The tones are shifted to fill the range. I suspect this shifting is where we can see some funkiness.

bob

[Bob McCarthy]

or change our 8 bit files to 16 bit before making any tonal corrections.

Sandy

I don't believe this causes the desired effect.

When you change 8 bit data to 16, you still have 256 steps, but each step has 256 points all with the same value.

This is still 8 bit gradation. Capture at 16 bit to get the smoothness promised by 16 bit.

bob

[sanking]

I don't believe this causes the desired effect.

When you change 8 bit data to 16, you still have 256 steps, but each step has 256 points all with the same value.

This is still 8 bit gradation. Capture at 16 bit to get the smoothness promised by 16 bit.

bob

Yes, if you change an 8 bit file to 16 bit you still only have 256 gradations, but changing to 16 bit prevents farther loss of gradations that you get when making tonal adjustments with 8 bit files due top rounding up and down to the nearest tonal value number. And unless you are printing with a 16 bit driver you have to convert the file to 8 bit any way before printing.

I am not theorizing about the benefits of converting 8 bit files to 16 bits before doing any tonal manipulations. It is my primary work flow in processing scans of large sheet film with my Eversmart Pro, which only saves in 8 bit. I find that I can do a huge amount of tonal manipulation with these files if first I convert them to 16 bit, not so with 8 bit as they break down very quickly.

Sandy

[Bob McCarthy]

Yes, if you change an 8 bit file to 16 bit you still only have 256 gradations, but changing to 16 bit prevents farther loss of gradations that you get when making tonal adjustments with 8 bit files due top rounding up and down to the nearest tonal value number. And unless you are printing with a 16 bit driver you have to convert the file to 8 bit any way before printing.

I am not theorizing about the benefits of converting 8 bit files to 16 bits before doing any tonal manipulations. It is my primary work flow in processing scans of large sheet film with my Eversmart Pro, which only saves in 8 bit. I find that I can do a huge amount of tonal manipulation with these files if first I convert them to 16 bit, not so with 8 bit as they break down very quickly.

Sandy

Don't know if this helps you , but ColorGenius (Screen Cezanne) only saves in 8 bit when scanning in greyscale, but if I chose RGB positive it will allow 16 bit scans which I can invert and convert to greyscale. I'm certain if your Creo did the same you would have picked that up along the way. Just in case...

bob