Originally Posted by rlwings
I am now using Calman with 21 point sweeps to 'see what's going on'.
Regarding your idea of making RGB changes equal and all at the same time. Do you mean IRE 1 through IRE 10 should each receive the same changes, or do you mean each individual IRE's RGB should receive the same changes?
How do I 'flatten' the final result if all are adjusted the same? Will this not leave inaccuracies?
Finally, if I am changing all IRE's at the same time, how do I know how much to change them without the interactive guide to show me as I go? Just guess? Seems like a lot of a lot of back and forth.
Hi, when you calibrate displays, it can happen to experience some issues which will try to make your calibrate time more painful.
There many issues you can experience like:
1) Mismatch of calibration controls adjustments of the display related with the patterns you are displaying and correcting, so an un-align of calibration controls affecting area.
2) When you display a static pattern for over some xx seconds, the display will enter to a dim mode, since it will see that you display the same static frame, to prevent temperature increase of panel or to power save to reduce the power consumption etc...it can dim the pattern.... so this can affect your adjustments decisions and not make them stable, becasue when you will re-measure with grayscale sweep you will see different results with the ones you had when you were calibrating a specific xx% gray pattern.
3) An adjustment of one point, can affect nearby points. So it can uncalibrate nearby when they are already calibrated.
4) OSD menus open while you measure a specific grayscale patch can affect the display output, so to have different results with OSD On/Off.
5) Large adjustment differences between 2 points; for example between 50 and 40% Gray RGB balance, it can increase the error to 45% Gray; so when you will look a grayscale ramp after the finished the 10-Point Grayscale calibration you can see a lot of issues to the gradation.
6) Extensive usage of calibration controls with random combinations of large scale can add processing issue to the image, with real content or color ramps etc.
For all these problem (I'm thinking right now) I recommend to take a full grayscale sweep and then examine the charts of RGB balance and gamma and imagine what adjustments you believe it will be better to apply to the whole grayscale adjustments controls at once and then re-measure the whole grayscale again.
For that reason to my calibration disk, all the gray/color patterns have maximum of 10 seconds duration (while I have chapters where the patches are autochange per 2 or 6 seconds also), I don't have 2 minutes for example of the same patch, to prevent the users for doing calibration OSD open (sometimes it's required, so you can pause) and stay to the same pattern for a long time. I haven't used numbers inside or outside the patch window, to say what pattern are you measuring (I use pattern announcement screens before each pattern)...external pattern generators don't use text notes for each pattern for example.
With that method, when you will be more familiar, it will provide you better visual results (beyond measurements...where they can be perfect looking by using any method).
Start from measuring all color temp modes (and them gamma modes) to see which one is closer to your target White Point and Gamma, the selection which will require less adjustments from you side.
For example when you will measure with grayscale sweep and you will see that you have ~10% more Red to most of the grayscale points you measure, you can correct that with many ways.....someone can:
1) Reduce for example -5 from Red slider and leave untouched the Blue/Green
2) or keep Red untouched but add +2 Green and +5 of Blue.
3) or reduce -2 Red but add +1 Green and +2 to Blue.
There many combinations you can do, also about what range of controls you have to tweak is related with each display design....its something you have to check....for example add or remove only 5 to a whole colorchannel and then re-measure with grayscale sweep to see how the RGB balance affected by these changes.
So when you will calibrate keeping the same 'strategy' of adjustments and keep a logic between grayscale RGB balance controls, the correction will be smoother and look better visually, since the processing of the display will be more linear.
A note for those who are addicted with Color Temperature charts.....when you see the RGB Balance Chart of a calibration software and you see the three (R/G/B) Channels Bars at exact 100% = 0 dE; doesn't mean that you have used equal percentage of each color channel.
The calibration software it's doing the normalizing internally according to the selected colorspace target options to give you better presentation for easier calibration.
D65 White Point for REC.709 (BD Movies) Color Space is using Red 21.27%, Green 71.52%, Blue 7.22% which gives 6504K.
REC.601 (PAL...EU DVD) D65: Red 22.20%, Green 70.67%, Blue 7.13% which gives 6504K.
REC.601 (NTSC... US DVD) D65: Red 21.24%, Green 70.11%, Blue 8.66% which gives 6504K.
REC.2020 (UltraHD Movies) D65: Red 26.27%, Green 67.80%, Blue 5.93% which gives 6504K.
All these colorspaces are using D65 as reference white point.
It happens (the most times) that the Warm1/2 of the consumer TVs (because coming not calibrated from their factory) to be closest mode when you have D65 White Point as a target, so for someone without measuring instruments, he is choosing one of those modes, these factory modes as selections are still providing uncalibrated picture.
When you have instruments/software, you can even make the 'cool' preset to match D65 White point, just it's better make less adjustments while you calibrating because some times large adjustments of the sliders can introduce problems like distortions, discolorations, clipping, banding, posterization....etc.
We use D65 (which has been created with specific mixture of RGB) which has 6504K because this is the white point the movies has been mastered (BD/UHD).
Each colorspace (REC.709 for BD / REC.2020 for UHD) while they have the same xy cordinates to create the D65, it's using different mixture of RGB colors channels, while all they report 6504K.
You can have 6504K temperature with different RGB channels mixture.
When you are using a meter/calibration software but you check only the Color Temperature Chart for the Grayscale, while the Color Temperature Graph can be perfect, the same time the RGB Balance Chart can be off.
This is happening because just a number 6504K is not the same as when we say D65 for a specific colorspace.
So when you are adjusting RGB balance controls, the Green channel adjustment is affecting more the luminance compared to the other 2 color channels, also when you reduce equally a specific point RGB sliders (-5 to all RGB sliders of 40% control for example), it can undo your RGB balance, all these stuff after practicing, testing, measuring, the user is improving it's calibration skills.....there no end for calibration, every day you learn something new