Matte in black in any cms’ software

Home Forums Help and Support Matte in black in any cms’ software

Viewing 2 posts - 16 through 17 (of 17 total)
  • Author
    Posts
  • #141455

    Ben
    Participant
    • Offline

    I do not think the black of a screen is that black.  Purely scotopic vision occurs if the input luminance stays below 10−3 cd/m2  .    Oled is a lot closer.     Can you see RGB 1,0,0 different than RGB 0,1,0 ?   It seems black to me mostly.    Maybe it is scotopic in my room with a window and light comeing in.  https://www.rp-photonics.com/scotopic_and_photopic_vision.html   .    I had to turn down the backlight.    Some show had black bars you could see and a black above that bar you could not see.    It was a very dark show  seeing the backlight made all the difference and seeing black and seeing black in the picture you could tell it was meant to be black.   Funny they showed it with black above black.   TV do mess up and underlight rgb 1,1,1 .   Setting 1,1,1 to show nothing in that show made everything better.

    I wonder where photopic starts ?      Well now we are on pho topic. lol

    #141456

    Guillaume
    Participant
    • Offline

    Photopic: This term refers to cone vision and generally covers adaptation levels of 3 candelas per square meter (cd/m2) and higher. Adaptation level is the overall brightness of your environment that your eyes have adjusted to. Translated into illuminance, if the average reflectance of your environment is 30%, an adaptation level of 3 cd/m2 (candelas per square meter) would result from illuminance of approximately 30 lux (3 footcandles). The combined peak sensitivity of the cones is at 555 nm, in the yellow-green part of the visible spectrum. (See red curve in figure.) The lumen, the basic metric of visible light, is defined by the combined cone response only.

    Mesopic: This term refers to a range of human vision with both rods and cones active. There is no hard-line transition at either end, but for most intents and purposes the mesopic range is generally considered to be from 3 cd/m2 down to 0.01 cd/m2.

    Scotopic: This term refers to rod vision and corresponds to an adaptation level below 0.01 cd/m2. The peak sensitivity of the rods is at 507 nm, in the blue-green part of the visible spectrum. (See blue curve in figure.) While there may be some (very little) cone activity at 0.01 cd/m2, once the light level drops to 0.001 cd/m2, only the rods are active. At this point, the ability to discern colors is gone. In addition, since there are no rods at the fovea and the cones there are not receiving enough light to be stimulated, the ability to discern fine details is gone. This light level is what you will find on a moonless night out in the desert, far from any town or highway luminaires. Drive out, turn off the car lights, and wait for your eyes to adapt. With light only from the stars overhead, you will be able to see large objects like boulders and shrubs and perhaps a rabbit scampering by. But no colors, and you can’t read the newspaper!

    Because of this difference in spectral sensitivity, the lumen, defined according to the cone response only, is not a very good measure of visibility at low light levels. As the light level drops, our peak visual sensitivity shifts toward the blue end of the visible spectrum. For most nighttime applications, it is in the mesopic range, with the peak being somewhere between yellow-green and blue-green. The lower the light level, the greater shift away from the photopic sensitivity curve.

    Source : https://docs.agi32.com/AGi32/Content/references/Photopic_Mesopic_Scotopic_-_Concepts.htm

    In fact if you’re in a dark room, there will be a higher dynamic range, but if you’re in pure photopic vision you’ll get shadow crushs where some objectively not that low luminance will appear dark.

    FIGURE 242: Eye brightness response over the range of intensities, from photopic threshold to the level of discomfort (based on Brightness function: Effects of adaptation, Stevens and Stevens, 1963). Luminance is given in decibels (dB), with 0 dB set at 10-7 mL, or 0.31 μcd/m2 (since the value in decibels is given by 10log(I/It), where I is some arbitrary intensity equal to or larger than the threshold intensity It (any 10 dB differential implies a 10-fold change in intensity or, for x as the dB differential, the corresponding intensities ratio is 100.1x ). Apparent brightness is given in brils (bril is a unit of psychological scale introduced by S.S. Stevens, defined as apparent brightness resulting from a 5-degree white patch of 40dB – equaling 0.001mL, or 0.000314 cd/m2 – luminance seen by dark-adapted eye in a brief exposure). Each individual plot is a form of B=k(I-It)a power function – so logB=alog(I-It)+logk) – with the constants k and a varying with the change in luminance, so that the curve fits experimental data for given level of adaptation (i.e. luminance level). Adding threshold intensity It to the power function results in the straight line of a power function plot on a log-log graph quickly turning down when approaching the threshold level. As the luminance increases, the intercept k decreases (from 10 at fully dark-adapted eye), resulting in lowering of the straight portion of the plot; at the same time, the exponent a increases, resulting in steeper slope of the straight portion (from 0.33 near the rods threshold, to 0.44 for 84dB threshold. While sufficient change in luminance intensity inevitably causes shift in the adaptation level, with the corresponding change in the threshold level, graph suggests that any given luminous intensity will appear brighter the lower level of initial adaptation, but the rate of increase in apparent brightness with the intensity is higher for higher level of adaptation. Interpolating through the points of apparent brightness for each adaptation level plot forms a non-power curve that describes eye brightness response over an extended range of luminous intensities (dotted red).

    That’s why theaters target a dark room for critical viewing conditions to shut down photopic vision thresholds. You’ll get the highest dynamic range possible from your vision. If ‘you’re forced to be in photopic vision, the best is to increase the backlight levels and play with blacks and whites levels to match the darkroom viewing conditions. If you have OLED based displays you ganna have to target the BT1886 EOTF because of elevated blacks for seemless viewing conditions. The idea of Dolby IQ and HGiG is to automatize the process but for HDR. But for SDR, it depends on the context. If you want to use your monitor for printing with a dedicated lightbooth, the thing you will have to do is to match the luminance of your monitor and the lightbooth and uniformise your lighting conditions of your room because the paper will be viewing conditions dependent. Where with digital content viewing conditions the goal is to tailor the monitor to lighting conditions.

    • This reply was modified 2 weeks, 6 days ago by Guillaume.
    • This reply was modified 2 weeks, 6 days ago by Guillaume.
Viewing 2 posts - 16 through 17 (of 17 total)

You must be logged in to reply to this topic.

Log in or Register

Display Calibration and Characterization powered by ArgyllCMS