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Author Topic: How to assess Black Level  (Read 5179 times)
Nino Loss
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« on: August 17, 2010, 04:26:16 PM »
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Hi,

With my PA241 I have the possibility to set the Black level  with the Multiprofiler. I just don't know how to find out a good black level. Visual assessment seams difficult to me.

thanks for any help

nino
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tho_mas
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« Reply #1 on: August 17, 2010, 05:20:25 PM »
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With my PA241 I have the possibility to set the Black level  with the Multiprofiler. I just don't know how to find out a good black level. Visual assessment seams difficult to me.
there are three main reasons to boost the black point ... if the monitor is used to edit print related images (for video editing it's completely different):
1.) all the measurment devices have accuracy issues at very dark onal values. the higher the black point the better (i.e. more accurate) the calibration curve
2.) too high contrast is tiring for the eyes. Too, you won't see "more" at higher contrast (rather the contrary)
3.) monitors have a much higher contrast than prints. boosting the black level will bring the monitor closer to a contrast similar to that of a print (photo print).

I am currently working with a contrast at around 1:340 and that's quite good here for me.
So... when the brightness of your monitor is somwhere around 120cd/qm you should try 0.3cd/qm for the black level. Contrast ratio will be around 400:1 then. If your monitor is closer to 160cd/qm you should try 0.4 for the black level to end up with the same contrast ratio.
Don't worry f the contrast is lower than 1:400. But it should definitely not be less than 1:256.


« Last Edit: August 17, 2010, 05:23:36 PM by tho_mas » Logged
Nino Loss
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« Reply #2 on: August 17, 2010, 05:40:14 PM »
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there are three main reasons to boost the black point ... if the monitor is used to edit print related images (for video editing it's completely different):
1.) all the measurment devices have accuracy issues at very dark onal values. the higher the black point the better (i.e. more accurate) the calibration curve
2.) too high contrast is tiring for the eyes. Too, you won't see "more" at higher contrast (rather the contrary)
3.) monitors have a much higher contrast than prints. boosting the black level will bring the monitor closer to a contrast similar to that of a print (photo print).

I am currently working with a contrast at around 1:340 and that's quite good here for me.
So... when the brightness of your monitor is somwhere around 120cd/qm you should try 0.3cd/qm for the black level. Contrast ratio will be around 400:1 then. If your monitor is closer to 160cd/qm you should try 0.4 for the black level to end up with the same contrast ratio.
Don't worry f the contrast is lower than 1:400. But it should definitely not be less than 1:256.



Sorry I forgot to say, that I talk about a monitor that I use exclusively for processing Raw files and printing from PS via soft proof.

Right now my PA241 is at 100cd/m2 and 0.2.
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tho_mas
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« Reply #3 on: August 17, 2010, 05:50:18 PM »
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Sorry I forgot to say, that I talk about a monitor that I use exclusively for processing Raw files and printing from PS via soft proof.
Right now my PA241 is at 100cd/m2 and 0.2.
well, print related then.
Set the black level to 0.3 cd/qm and see if you like it. Maybe you have to get used to it ... but I'd recommend to judge about the outcome not only from looking at the monitor for a few minutes but from going through the whole process of RAW-editing->PS editing->softproofing->printing->comparing the final prints to the monitor view (in softproof mode, of course).
You will see that swichting to softproof (where the black point of the display is further boosted to the black point of the print paper) is far less different to the view without softproof than before. Simply as the black point is already higher. Exactly that is what it is about...
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WombatHorror
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« Reply #4 on: August 17, 2010, 10:21:18 PM »
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Hi,

With my PA241 I have the possibility to set the Black level  with the Multiprofiler. I just don't know how to find out a good black level. Visual assessment seams difficult to me.

thanks for any help

nino

Normally you always want it as dark as possible, as it is even this IPS doesn't get all that dark.

The only time you ever want to mess with that is if proofing a print and wanting to see on screen the same faded black levels of the paper you are using. It can certainly be useful for that and many use it then. But you don't want to edit like that it just turns your shadows to mush and you're gonna be really, REALLy shocked once LCD goes by the wayside and OLED or whatever eventually takes over.

Generally raising it just kills the already mediocre black response though and is to be avoided.
The PVA with the deepest blacks easily go 4-6 TIMES darker and OLED goes essentially infinitely darker if viewed in a pitch black room.


I know all the nothing counts but a prints and that is the one and only way to ever view anything and screen viewing and future tech are to be ignored crowd won't agree with me though. Smiley

« Last Edit: August 17, 2010, 10:26:55 PM by LarryBaum » Logged
WombatHorror
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« Reply #5 on: August 17, 2010, 10:25:18 PM »
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Sorry I forgot to say, that I talk about a monitor that I use exclusively for processing Raw files and printing from PS via soft proof.

Right now my PA241 is at 100cd/m2 and 0.2.

I would honestly leave black level at minimum and edit in a darkish room at maybe 90cd/m^2 and you might get down to 0.12-0.16 black depending. Use compensation level 4? That really depends upon your copy, maybe you don't need it so high or maybe need it even at 5.

Then for proofing I would raise the blacks and try to get the contrast ratio close to the paper you are using.

I suppose if you are proofing for printing only and never plan to print with some advanced tech in the future or view on some 5k super monitor in 10 years you could skip the keep black minimum and just do everything in proof mode.
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tho_mas
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« Reply #6 on: August 18, 2010, 03:40:14 AM »
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The issue with too high contrast is that you can't differentiate dark tonal values anymore.
It has nothing to do with technology … our eyes are always adapting to white… i.e. the brightest tones.

An (exaggerated) example: you are hiking on a glacier. Down in the valley you stop off in a mountain hut to drink a cup of tea.
The first minutes you won't see anything inside the hut. You first have to adopt to the much lower brightness level.
Actually it's similar on a monitor: the higher the contrast the harder it is to differentiate dark tonal values.
It's up to you to find out the contrast ratio when you start to see less differentiation in dark tonal transitions.
A contrast ratio of 1:1000 (e.g. at 100cd/qm white & 0.1cd/qm black) won't help you to differentiate dark tonal values… unless you zoom in at 100% to eye up the dark tonal areas of the image and wait a short while to get adopted to that darker part of the image.
Of course the contrast should not be so low that dark tonal values are mushy.
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Nino Loss
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« Reply #7 on: August 18, 2010, 12:00:26 PM »
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The issue with too high contrast is that you can't differentiate dark tonal values anymore.
It has nothing to do with technology … our eyes are always adapting to white… i.e. the brightest tones.

An (exaggerated) example: you are hiking on a glacier. Down in the valley you stop off in a mountain hut to drink a cup of tea.
The first minutes you won't see anything inside the hut. You first have to adopt to the much lower brightness level.
Actually it's similar on a monitor: the higher the contrast the harder it is to differentiate dark tonal values.
It's up to you to find out the contrast ratio when you start to see less differentiation in dark tonal transitions.
A contrast ratio of 1:1000 (e.g. at 100cd/qm white & 0.1cd/qm black) won't help you to differentiate dark tonal values… unless you zoom in at 100% to eye up the dark tonal areas of the image and wait a short while to get adopted to that darker part of the image.
Of course the contrast should not be so low that dark tonal values are mushy.


That makes sens, thank you.

After reading your posts and rethinking my way of doing, I did a very extreme test yesterday and it work out perfect.

First the monitor is at 5000K and 1.8. Comparing the paper white of CIFA Platine to the screen took me to 130cd/m2. After an initial print I compared the result with the screen in order to get an idea for the black level, which I ended up by setting to 0.9!!! I did another print and the result was a perfect match. Maybe my methode has some major flaws, but it worked out perfect.

After this I wanted to try a much easier paper, which is CIFA Baryta Photographique. First I went back to 120 (which turned out to be to dark, as my print came out quite a bit brighter than my screen) and 0.3. This match is quite impressive too.

Seams like I have to configure the monitor for each paper differently.

regards

nino
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tho_mas
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« Reply #8 on: August 18, 2010, 02:16:20 PM »
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Seams like I have to configure the monitor for each paper differently.
Strictly speaking this would be ideal. But it is not very practicable.
I'd simply set a black point, i.e. contrast ratio, that is comfortable to work with and that is not too far away from your preferred paper.
The remaining difference will be leveled out when you active "simulate black ink" in the softproof setting.
« Last Edit: August 18, 2010, 02:18:02 PM by tho_mas » Logged
Nino Loss
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« Reply #9 on: August 18, 2010, 02:25:29 PM »
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Strictly speaking this would be ideal. But it is not very practicable. [...]

Why? With NEC's MultiProfiler, its literally one click to bring up the control panel. Than you just dial in white and black levels directly or called up a preset!

Also the PA241's 3D-LUT can simulate the paper directly. For the moment this is still new to me. I did try it out and loaded a profile into the monitor, but somehow the result, I mean the final print, was not so convincing.


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tho_mas
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« Reply #10 on: August 18, 2010, 03:00:19 PM »
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Why? With NEC's MultiProfiler, its literally one click to bring up the control panel. Than you just dial in white and black levels directly or called up a preset!
well, okay. Similar to Eizos Color Navigator, obviously.
If you want to go that way that's doable. However, I think you need a kind of "standard" for you to work with. I.e. to edit your images without taking a certain paper into account. Or in other words: to edit your "master files" independently from any print. And I think a contrast ratio of around 1:400 or a little less is quite good - it's not too far away from a print but still high enough to see all tonal values clear enough.
From then on, i.e. when preparing the file for a certain print, you may very well switch to a monitor profile that is tweaked with regard to a certain paper.
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Nino Loss
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« Reply #11 on: August 18, 2010, 03:12:01 PM »
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well, okay. Similar to Eizos Color Navigator, obviously.
If you want to go that way that's doable. However, I think you need a kind of "standard" for you to work with. I.e. to edit your images without taking a certain paper into account. Or in other words: to edit your "master files" independently from any print. And I think a contrast ratio of around 1:400 or a little less is quite good - it's not too far away from a print but still high enough to see all tonal values clear enough.
From then on, i.e. when preparing the file for a certain print, you may very well switch to a monitor profile that is tweaked with regard to a certain paper.


I hear. I will do like that. Its close to what Larry suggested. Ill create a master/standard mode for editing the images independently of the paper.  I wonder how I will choose white and black levels? Maybe an avarage of all the papers I regularly use. Something like 120/0.3or more like what Larry said, 90cd/m2 in a dark room with black to minimum?

I would honestly leave black level at minimum and edit in a darkish room at maybe 90cd/m^2 and you might get down to 0.12-0.16 black depending. Use compensation level 4? That really depends upon your copy, maybe you don't need it so high or maybe need it even at 5.

Then for proofing I would raise the blacks and try to get the contrast ratio close to the paper you are using.
[...]

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Czornyj
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« Reply #12 on: August 18, 2010, 03:24:33 PM »
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I hear. I will do like that. Its close to what Larry suggested. Ill create a master/standard mode for editing the images independently of the paper.  I wonder how I will choose white and black levels? Maybe an avarage of all the papers I regularly use. Something like 120/0.3or more like what Larry said, 90cd/m2 in a dark room with black to minimum?


Try ~120cd/m^2 / min. blackpoint, and turn on softproofing with with enabled "Simulate Paper Color" option.
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tho_mas
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« Reply #13 on: August 18, 2010, 03:29:19 PM »
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Try ~120cd/m^2 / min. blackpoint, and turn on softproofing with with enabled "Simulate Paper Color" option.
the latter highly depends on the paper profiles and also on the calibration of the monitor...
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tho_mas
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« Reply #14 on: August 18, 2010, 03:35:16 PM »
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black to minimum?
depends on the software (I don't know the NEC software). If "minimum" means the deepest black, than that's BS. If anything, the deepest "neutral" black is appropriate... i.e. a black that is calibrated to the white point of your calibration target.
Simply try it... I'd say at 120cd/qm to 100cd/qm 0.3cd/qm is okay. Below I'd go for 0.2cd/qm... or, if the software allows you to set a luminance level and a conrast ratio, simply set 1:400 as contrast (the software will calculate the black point then).
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Nino Loss
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« Reply #15 on: August 18, 2010, 10:58:12 PM »
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I am experimenting with all your suggestions.

As my NEC PA241 is able to simulate  the paper by loading the profile into the 3D LUT, there are a lot more possibilities. Does anybody actually work with this already?
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WombatHorror
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« Reply #16 on: August 19, 2010, 01:52:50 AM »
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The issue with too high contrast is that you can't differentiate dark tonal values anymore.
It has nothing to do with technology … our eyes are always adapting to white… i.e. the brightest tones.

An (exaggerated) example: you are hiking on a glacier. Down in the valley you stop off in a mountain hut to drink a cup of tea.
The first minutes you won't see anything inside the hut. You first have to adopt to the much lower brightness level.
Actually it's similar on a monitor: the higher the contrast the harder it is to differentiate dark tonal values.
It's up to you to find out the contrast ratio when you start to see less differentiation in dark tonal transitions.
A contrast ratio of 1:1000 (e.g. at 100cd/qm white & 0.1cd/qm black) won't help you to differentiate dark tonal values… unless you zoom in at 100% to eye up the dark tonal areas of the image and wait a short while to get adopted to that darker part of the image.
Of course the contrast should not be so low that dark tonal values are mushy.


I still don't think editing everything in an artificially reduced CR is necessarily ideal.
You can zoom in a little to check fine shadow detail if need be.
If you set the black point way up all you do is turn instead of a few a whole ton of shades at the bottom to all look like 0,0,0 (absolute profile) or if you use relative well all I can say is you find things looking way to pitch black if you view them on some 5k OLED in the future or display them in some other method than a current print.
And I certainly wouldn't set it that for screen viewing of images.
Our eyes have a pretty large dynamic range, way larger than 1000:1 so you won't need any time for eyes to adjust, if the dark details or too small and close to a bright patch then just zoom in a bit.
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tho_mas
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« Reply #17 on: August 19, 2010, 03:28:56 AM »
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If you set the black point way up all you do is turn instead of a few a whole ton of shades at the bottom to all look like 0,0,0 (absolute profile) or if you use relative well all I can say is you find things looking way to pitch black if you view them on some 5k OLED in the future or display them in some other method than a current print.
actually, no, this will not happen in a color managed workflow. The black range is not clipped... you still see the full range of tonal values from pure black to pure white. The black is just not as dark.
Actually 0.3cd/qm is a black level that a lot of IPS panels produce in preset... they simply can't go lower.
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WombatHorror
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« Reply #18 on: August 19, 2010, 02:38:25 PM »
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actually, no, this will not happen in a color managed workflow. The black range is not clipped... you still see the full range of tonal values from pure black to pure white. The black is just not as dark.
Actually 0.3cd/qm is a black level that a lot of IPS panels produce in preset... they simply can't go lower.

It depends if a relative or absolute black point is being used.
And yes if you use relative there will still be the full range of shades shown, but then the photo also looks rather different in the deep shadows/dark parts from monitor to monitor or paper to paper or whatnot. And things that were supposed to look merely dark will suddenly look pitch black as deep space on future OLEDs.

Maybe many IPS can't go lower than 0.3 but that doesn't mean it's a great stat. Many of the new ones go to at least .2 and the NEC PA go to around .12-.15 depending upon what you measure with. And one of the new Eizos, a PVA, goes to around 0.02!
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Nino Loss
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« Reply #19 on: August 19, 2010, 06:38:14 PM »
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I have tried both ways. IMHO leaving black point at minimum gives me an easy way to "see what's in the file". So when it comes to soft-proofing with PS, I can see where I want to go with my file for the print (but where I'll never succeed to get to ;-) . The advantage for me of setting black levels to match the paper is a very accurate soft-proof. Only, I found that  the latter does not work so well for me with papers that have poor blacks, like matte papers, because to simulate them I had to lift the black levels considerably, which ends up mashing the blacks (But maybe simulations via 3D LUTs are better?!).

My original question was nonetheless a bit different. What would be a good way of assessing the black level. So it turned out that the question is more complex. We could measure/approximate paper black capabilities. That would make me having a profile/preset for each paper. We could leave everything at minimum to see all there is in those files. Or one could aim for the aforementioned 1:400 ratio as compromise between print and screen? These are three very different approaches.

If you work for inhouse inkjet printing (which is what I do), it could be that an ideal work-flow would make use of all three.
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