How can I disable auto hue change: Redshift/Display Control? (Bionicpup64 8.0)

[mikewalsh]

@vtpup :-

But Mike, that doesn't make sense, even if color blind -- you can still turn down the blue and turn up the red, and that has the same effect on the monitor's pixels as the other methods.

Oh, I couldn't agree more. Makes no sense at all. But I tell ya this much; you wouldn't want to try looking at the world through MY eyes, mate. It'd drive you nuts!

Mike.

[vtpup]

Clarification so you don't think the above was in any way meant negatively/personally ie "snottily". By not making sense, I meant again literally, that one (you) should be able to experience the same screen characteristics using either method of adjustment, assuming the red, blue and green levels are set the same in both.

What wouldn't make sense is that the experience would in any way be different only because the adjustment program was different.

[vtpup]

Heh, cross posting..... okay just out of curiosity, Mike, do you happen to know what setting, numerically, in Display Control is most comfortable for you?

[mikewalsh]

Heh, cross posting..... okay just out of curiosity, Mike, do you happen to know what setting, numerically, in Display Control is most comfortable for you?

Couldn't tell you, mate. AFAIK, it's exclusive to the new 3-series JWMDesk. I tried it briefly, and didn't like what Roger's done with it. So I've reverted to 2.4.3; my favourite out of the bunch, in widespread use across the kennels. It doesn't have DisplayControl; I use my ScreenControl instead.

Mike.

[vtpup]

Oh, okay, so I'm getting confused about Display Control vs Screen Control, and for anyone else possibly confused as well, we are no longer talking about Redshift here -- which is a dynamically changing red/blue tint shifter. We're just talking about static screen tint adjusters.

Now I'm going to have to look up Screen Control to understand what we're talking about (at this point.....)

[vtpup]

Okay, Mike, I misunderstood that you were talking about a choice of yours to use an optional program you were developing called Screen Control vs the problem I was having caused by a recent version of the Desk Manager called, similarly, "Display Control". And problems caused by Display Control ( and Redshift) was the reason for this thread.

Interestingly this brings up the topic of just what is Hue Adjustment, Color Temperature, and Monitor Calibration, since they all mean and do different things. A lack of understanding about what they are has caused Display Control to create issues with Monitor Calibration. So I'm going to try to clarify what and why these terms are important to understand.

Screen colors are produced by a combination of red, green, and blue pixels, which are the primary colors of generated light. This is different than the primary colors of reflected light that everyone learned in school using poster paint of red yellow and blue. In computers, for example, to produce the sensation of pure yellow on a screen a computer combines red and green adjacent pixels and blocks blue.

Because there are three colors of pixels on a computer screen, any available screen color (hue or tint) can be produced by changing the relative values of three brightness variables, one for red pixels, one for green pixels and one for blue pixels.

This is exactly how Puppy's "Monitor Gamma Calibration" program works. It provides a scale of -100 to 0 to +100 for brightness for each of the three monitor pixel colors. The default is 0 for each.

Monitors are almost never perfectly color balanced. Color balancing a monitor is the purpose of this program. It is important to color balance your monitor if you are editing and publishing photographs or videos so that they will look to others the way they look to you, and so that printing will have a good chance of looking like what you saw in your editing program. It is also to be hoped that others will color correct their monitors, or at least the manufacturers have done a reasonable job so we all see about the same thing when looking at the same image.

In practice, while color balancing, if your monitor seems too blue, you would reduce the blue level until it looks right to you. Maybe it then still has a slight greenish hue, so you reduce the green level a small amount to warm it up, relatively, because with blue reduced a lot, and green reduced a little, red is still at full strength. You can see the result especially, I find, by focusing on the gray patch in the program. That should look like a neutral gray.

Okay, this is getting long, I'm going to split this up into a couple of posts..... TBC

[vtpup]

I've just checked my own Monitor Gamma Calibration values for this old Acer laptop and I have set the following :
0 Red, -4 Green, -24 Blue
. That gives me a neutral gray (to my eyes) so, in my case the monitor was way too blue to start with, and somewhat greenish.

The key point to keep in mind here is that there are three adjustments that you can make independent of each other.

Now, let's talk about Color Temperature. Color temperature is a complex subject, with many different fields of use and understanding, and therefore it is a confusing subject. But one aspect is definite -- it describes a very limited spectrum of light, which does NOT include green or purple. The actual spectrum described by "color temperature is basically a range from blue to orange. It's main value lies in talking about lighting. If you were to use your computer screen as a light source in your house, then color temperature would be important.

But we aren't. We are looking at images videos and text, and we want their rendition to be full spectrum, and balanced. Nevertheless, lately there have been popular computer tint adjusters that feature a color temperature slider to set a "screen color temperature".

Well, first of all, they can't really turn your screen into a sunlight or incandescent, etc. equivalent light source. These controls feature just a sliding scale of orange and blue filters with labels that use the term "Kelvin" to describe arbitrary numbers along a scale. Your computer is not actually doing anything like producing an equivalent number of "K" shown on a typical "color temperature" scale. Your computer is producing a wide and varied spectrum of light in an image, skewed by whatever monitor characteristics it has, modified by whatever monitor gamma corrections you've added.

In other words, these control should just be labeled Blue-Orange Tinters. They are NOT a replacement for adjusting the three monitor pixel colors for correcting monitor display rendition. Using a color temperature control is pretty much like putting on colored sunglasses, where the available shades range only from orange to blue. You will kind of see other colors modified, but never actually be able to see the full range of real colors unless you take them off.

Okay, well no problem so far. If an orange or blue tinted screen somewhere in the available range looks good to you, that's no problem for you. Especially if you understand that you only have available a limited number of choices for screen rendition and appearance, and they will always be tinted in some way away from true colors. That's personal choice.

But the problem comes when people don't understand this, and Color Temperature is presented as the normal default monitor adjustment control. That's what happens in "Display Control". A single tint adjuster is presented. Orange to blue. There is no possibility of adjusting green, red and blue colors separately. There is no way to balance colors outside of the provided 2 variable range.

TBC

[vtpup]

Well, but isn't there? Doesn't Display Control include at the bottom of its window a button to actually invoke the Monitor Gamma Adjust program?

Well, yes it does. But many users will not understand the difference between color temperature and monitor color correction. This is opposite to the way it should be presented. Frankly, color correction should come first, and color temperature should be a secondary option. Three sliders are needed to fully control computer hue. One cannot. Three necessary variables cannot fit into a single duality.

In addition, even if a person wants a warm temperature filter in their screen, they should be able to adjust that monitor first into presenting colors in a balanced way before applying the filter. If your monitor is badly off to begin with, a color temperature filter is going to distort contrasts, and you may never find a pleasing or even reasonable setting. For instance if the monitor is too green, neither a blue or an orange filter will solve that. If that's the only control you have, how will you ever know it isn't allowing you to see things properly?

But an even bigger problem is that Display Control currently negates monitor correction instead of acting in concert with it. The action of Display Control, as mentioned earlier in the thread is to place a new set of monitor values inside a script in Puppy's Startup menu. Those values are based on the Color Temp slider alone. You can adjust Monitor Gamma Correction by clicking on its button, but whatever is set there will be ignored on the next boot.

Well, enough for now -- I know this is long, it's important to understand what these things mean and how they interact. While I haven't talked about Redshift above, the same thing applies to its filtering -- the difference is in dynamic filtering over time, but in two variables, again instead of three, and not in concert with monitor correction.

ps..And I think it does actually explain why, Mike, in your special case, there has been a visual difference between adjusting monitor calibration and using a color temperature control. I can imagine that it is easier to have a single control that adjusts the orange blue spectrum, particularly with blue green color-blindness.

[mikewalsh]

@vtpup :-

Not being "funny" when I say it, but I'd forgotten that folks like yourself do exist.....people who really ARE bothered by computer visual reproduction looking as natural and true-to-life as it's possible to get it.

I've had crap eyesight since I was about 3 years old. To this day, I haven't got the faintest idea whether the way I see the world around me bears any relationship to the way others see it.....seriously!

Personally, audio matters far more to me than video quality, though I do appreciate the range of adjustments available in VLC.....particularly the ability to 'sharpen' the video image. I learnt 3 or 4 musical instruments while still at school, and in my final years a few of us formed our own group, which we called "Stuffed Tomato"! Despite not having the long fingers perceived as necessary for playing the bass guitar, that was my instrument of choice; so I got introduced to the concepts of 'shortscale' necks, round-wound & flat-wound strings, humbucking pickups, and all the rest of it.

Jazz & blues have always been a favourite of mine, but my real love has always been reggae.....and bass is one of the important cornerstones of the whole reggae 'sound'. Look up guys like Linton Kwesi Johnson, Derrick Barnett, Val Douglas, Robbie Shakespeare & Aston "Family Man" Barrett, and you'll see what I'm on about.

(I was lucky enough to pick up a Rickenbacker shortscale 4000FL fretless, many years ago. My old Marshall 100-watt valve amp sits out in the garage, carefully cocooned, and the 'Rick' languishes in its case in the back of my wardrobe. Both very rarely get any use these days, but I'm loath to let 'em go. Ne'm mind.)

---------------------------------

Anyway; to prove that I do listen, and try to make my utilities usable by all, I've added the ability to call the Monitor Gamma Calibration tool straight from ScreenControl's tray icon context menu.....so you can set yr monitor up properly before using the 'tint' control, if you're concerned about such things. The "xgamma-gui" script appears to be standard fare in pretty much all Pups, so the menu entry should work in all of them without fuss.

It can be found here:-

viewtopic.php?t=6022

.....should you want to take a butchers at it.

Mike.

[vtpup]

We aren't so far apart there either, Mike....Stuffed Tomato? Hahaha! Mine was called "Pure Lard," played bass also, a Danelectro rewired by Dan Armstrong in the City, flat wound Gibson strings fit it....sort of. Lipstick pickups. Decades later I worked security for a Bob Marley Survival tour concert, still have the too small tee shirt with Marley on the front "Survival" and "Security" on the back. It was a cold winter night in Burlington, VT, we were outside for the first half, but inside for the second. Place went nuts, in a good way.

Sorry about the eyesight. I was a painter, so color was the world I lived in.