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Author Topic: How to visually gauge absolute black in nature and tone map it to output.  (Read 13145 times)

Tim Lookingbill

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Here's another observation to show how the relationship of a constantly changing black point within the process to final viewing pipeline that requires scaling to overall shadow densities.

Below is a shot of a mural and an inset shot 2 hours later of a section in shadow. It is a depiction of a night scene. The muralist didn't use absolute black paint to draw in the cracks of the rocks because of the extreme viewing light variances that would force the rocks to scale too dark for each extreme lighting conditions and to prevent the darker black cracks from looking posterized as I've shown by drawing in 0,0,0 black dashes.

Not saying you need to make your edits this light in the shadows. This is just a demonstration of an optical phenomenon regarding perception influenced by variances in black densities and how they relate to variances in dynamic range and light levels. Your transmissive display and your digital images of real scenes have a far bigger DR than that mural even when the mural is lit by bright sunlight, but a print has far less than the display but more than the mural due to both the lighting it's subjected to and the density of ink and obsorption=reflectance characteristics provided by the paper.

The black of a transmissive display has an infinite density, a black hole with regard to human perception, where as a print's black density is not, even though you think the black looks the same as the display's. It isn't especially under varying light levels.
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SZRitter

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So, are you worried about contrast in shadows for details, or the bottom black point?

For the bottom black point, you could easily take a curve and adjust it so the absolute black point comes up about 5% from true black. Adjust to taste.

For shadow contrast, you could add a luminosity mask into the darker tones and adjust their contrast through curves. My understanding of our ability to view detail is that it is based more upon contrast, either through color or luminosity, than anything else.
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Tim Lookingbill

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So, are you worried about contrast in shadows for details, or the bottom black point?...

...My understanding of our ability to view detail is that it is based more upon contrast, either through color or luminosity, than anything else.

You have a correct understanding of how we see shadow detail through contrast and definition by distinguishing separation in dark against light densities scaling up out of absolute black. And I'm aware of how to correct for that.

What I'm not aware and I have to remind myself with that shadow number reality check is to know just how light or dark to go in my edits because the appearance of black point density on a print which affects the relationship to lighter shadow detail will vary according to different viewing light levels AND whether the light is diffused or spot. OTOH the black density appearance on a transmissive display appears static editing to make the image look good but with the added problem of adaptation making me see the overall shadow area as looking light enough when it's really too dark to overcome the issues I just described about printed black and varying light.

The black dotted line I included in the shot of the mural remains static whether it's viewed in bright light or in shade but the shadow tones that make up the detail against the static black change not only in density but in contrast and flatness especially to changes in character of light. Note the tone density relationship of the cracks to rocks and plants and their shadows are less defined than the sunlit version meaning the character of light as viewed on a print under various lighting doesn't behave linearly like it does on a transmissive display.

I'm beginning to think a warning label needs to be printed on fine art framed prints displayed under perfectly lit gallery lighting that goes something like this...

"Warning: Gallery halogen light bulb not included with beautiful print. Not responsible for how it will look anywhere else without it".
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Steve House

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....
I'm beginning to think a warning label needs to be printed on fine art framed prints displayed under perfectly lit gallery lighting that goes something like this...

"Warning: Gallery halogen light bulb not included with beautiful print. Not responsible for how it will look anywhere else without it".
A humorous sentiment firmly grounded in two inescapable realities - A) your final critical evaluation of a print must be done with the hard-copy print itself, not its 'preview' on the screen; and B) the results are only valid for one specific set of viewing conditions.  A fine print may go through several iterations of the physical print until it's what the artist intends.  The screen might get you 95% there but the last 5% will be through trial and error with pilot prints coming off the printer using the same paper, ink, and size as will be used for the final print. And there are no viewing conditions one could create for that final evaluation process that would compensate for all possible variants in the print's final resting place.  Indeed, one fellow photographer I know maintains that profiling and calibrating one's screen and printer is non-essential since over time one can train the brain and the eye to get you as close as you can get with a calibrated system, since the final print adjustments need to be done referencing the physical print anyway.
« Last Edit: May 15, 2014, 09:31:18 am by Steve House »
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Tim Lookingbill

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A humorous sentiment firmly grounded in two inescapable realities - A) your final critical evaluation of a print must be done with the hard-copy print itself, not its 'preview' on the screen; and B) the results are only valid for one specific set of viewing conditions.  A fine print may go through several iterations of the physical print until it's what the artist intends.  The screen might get you 95% there but the last 5% will be through trial and error with pilot prints coming off the printer using the same paper, ink, and size as will be used for the final print. And there are no viewing conditions one could create for that final evaluation process that would compensate for all possible variants in the print's final resting place.  Indeed, one fellow photographer I know maintains that profiling and calibrating one's screen and printer is non-essential since over time one can train the brain and the eye to get you as close as you can get with a calibrated system, since the final print adjustments need to be done referencing the physical print anyway.

Wish I had the money to make all those pilot print iterations to match some subjective vision of an artist who seems to be working blind and very picky if they can't be satisfied with 95%. Could you or any one be able to distinguish between how much of that 5% is on account of the eye's adaptive nature as opposed to the influences of lighting and ink absorption and reflectance from the light on the print?

I can't tell if your comments are referring to production workflow practices to accommodate another artist's pickiness or you are referring to your own workflow habits both of which I don't share.

I don't seem to have to work that hard at producing a print that is viewable in my dim living room light but I now understand why I was having problems and I fixed them. And what I've shown in what I had to do to insure this required WAY MORE than a 5% change. Going from L*12 to L*24 in luminance in the shadows suggest I doubled the light, but as you can see from that orange flower, if I'ld done that the flower would have to appear as a pastel peachy off white. The reasons I understand why that didn't happen may be what's lacking in production workflows that require several iterations just to correct for 5%.

A static non-changing state of a calibrated system and matching light level viewing environment keeps one from going around in loops trying figure out why 5% difference is or isn't important. I'll admit I only print on 8x10 glossies because that's all I can afford. I printed on matte and was disappointed with the black levels and the overall reduced dynamics for viewing in my dimly lit living room, but I'm not producing prints on thousands of dollars of equipment and supplies for obvious reasons.

 
« Last Edit: May 15, 2014, 03:21:49 pm by Tim Lookingbill »
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