Originally Posted by Clemery76
I have a couple more calibration queries. I tend to be a bit verbose so will start with two simple questions, then give some context below:
1. Does anyone else find that the greyscale patterns (100%, 95%, etc...) don't quite line up to the IRE adjusters on their TV? (i.e. the 100 IRE slider will affect 95% white more than 100% white)
Hi, for that effect you see, it may be:
1) The difference of levels or RGB triplets of patterns you send with ones the TV expect from you to display. When you calibrate, you need the patterns you send to have exact same triplets (RGB or YCbCr) with the ones the software is expecting, if there mismatch, then you will have mismatch with controls affectibe range also.
When you display patterns from a notebook HDMI, you need specific settings (to notebook/TV) to be sure that the values are correct. (see 4
2) There display which are suffering with some issues related with a un-align of available calibration controls (10-Point RGB Balance) to the working effecting range of the signal, for example when you display a 50% Gray patch and you dial 50% Gray RGB balance, internally to the display its not changing the 50% of Gray but another level...for example 42% or 56% etc...just for example.)
This makes the calibration more difficult and you will always introduce anomalies when you will finish a 10-Point RGB balance and you display a Grayscale Ramp, there will be visible issues there with strange color-shades.
These specific values (to each display) of contrast/brightness controls which are align better the calibration controls and it will be helpful to measure with 21-Point Grayscale patterns when you calibrate using the available 10-Point controls you have. Doing this will be able to spot better any anomaly and prevent issues.
Its also a better idea to take full grayscale sweep and not do real-time adjustments, to be able to spot easier your adjustments how they affect the grayscale performance....so measure fully grayscale (with menu OSD off)....then look your RGB Balance / Gamma charts....open OSD...apply the adjustments you believe they will help...then close OSD and remeasure grayscale again.
To some displays, the RGB balance controls design in such way where they will align better to exact 10-p luminance levels when you will have contrast/brightness to default positions, to other models it will align better when you will have contrast at max position, this is something you need to test. That un-alignment can interact and shift each RGB balance controls to higher or lower affecting luminance range.
Originally Posted by Clemery76
2. My TV also has sliders to adjust gamma at 10 IRE increments. Should I use these to help smooth out the gamma and get a more accurate gamma line/curve, or is it best to avoid messing with the gamma too much, relying mainly on greyscale calibration?
Start with 2-Point RGB balance and do 100% White with RGB-Gain and 30% Gray with RGB-Offset controls, when you will do many back/forth until you have stable readings, you will move to 10-Point RGB balance, after your are ready with grayscale you will move to CMS calibration.
Originally Posted by Clemery76
OK... a bit of context. After attempting calibrations on three different TV's (one backlit LED, two OLEDs), I have always found that my IRE adjustment sliders on the TV never quite match the input greyscale patterns. This is true whether I'm using Colour HCFR patterns downloaded from the internet or patterns generated automatically in HCFR and sent via my laptop over HDMI. Additionally, I find that when I play the black clipping pattern through my laptop over HDMI, I cannot see 17 or below flash, no matter how much I increase the brightness on my TV, almost as though the PC is limiting the output, even though its set to full range. The same black clipping video played through my Minix U9-H media player through the same input displays properly, so I'm finding that I have to set brightness/contrast using these patterns on my Minix, before then switching to the laptop for the auto HCFR patterns.
But no matter the values, I just can't get the patters and IRE sliders to properly match up. e.g. I'll increase brightness by 5 points to 55, and contrast 6 points to 96. Then I'll try to adjust greyscale. At this level, I'll find that the 100IRe slider affects 95% white moreso than 100% white. But it is not linear, in that at the bottom range, the 20% grey patters results in no change when adjusting the 20 IRE slider, but the 10% grey will be greatly affected. AND, this is with HCFR set to output 0-255 (and laptop set to output full range), which is not really ideal for calibrating SDR.
I have found that if I greatly reduce brightness (down to around 35), then the bottom end lines up better, but then the top end doesn't get bright enough (I'd have to display 95% white to adjust the 90 IRE slider), and I also noted that there was visibly no change in white/brightness level between 95% and 100% white windows. I tried fiddling with the laptop output settings, and found that reducing the output gamma from 1.0 to 0.8 would bring it closer into line, but still far from accurate and would have to sacrifice either the top end or bottom end, as well as the gamma line looking more like an arch than with any other mode. As it stands, my current calibration was done using 0-255 output through HCFR with a bit of guestimation thrown in, and naturally the picture looks somewhat unnatural to me. Are there any tips for getting the grey patterns to line up with the IRE levels on the TV? My laptop is a Lenovo Yoga with an Intel HD Graphics 4400 inside, set to 1920x1080, 60hz, Full Range, 32bit colour depth, YCbCr disabled.
If you are using AVSHD, it has a mismatch to grayscale patterns (see more details reading the ''3'' here
), this can be fixed from inside HCFR with a software offset, see here what you can do to fix the issue: LG 2017 OLED Calibration Thread and Settings
Also the 4-Point Saturation of AVSHD is not compatible with HCFR (and there no fix about this), for example:
AVSHD 50% Red Saturation Pattern has RGB Triplet 190.95.95 but HCFR's Color Engine needs/calculates errors from RGB Triplet 191.96.96, it's 0.42 dE2000 error.
AVSHD 75% Magenta Saturation Pattern has RGB Triplet 203.100.203 but HCFR's Color Engine needs/calculates errors from RGB Triplet 202.99.202, it's 0.36 dE2000 error.
About the clipping below 17 you you experiencing is related with the fact that all HTPC software players are expanding by default the video signal (patterns/movies are using Video Levels aka 16-235) to data signal (PC's are using Data Levels aka 0-255), so when they are expanding, all levels 1-16 are becoming 0 and all levels 235-254 are becoming 255. (About the numbers of the flashing bars pattern.. the 1-16 looks like 16 and 235-253 looks as 235)
When you have a HTPC and you need to have the most accurate output settings, you need to create 2 presets to your display/projector, to do one calibration for video levels and one for PC levels.
For Movie/Pattern playback you will need video levels calibration since the content mastered for video levels, so you have to set your VGA output as RGB-Full, your software movie player to RGB-Video and your display/projector to receive RGB-Video.
This is the most accurate way, since you will not expand any content levels and you will left headroom for all levels above 235, do if you display a contrast pattern (for video levels) it will not clip, and it will show you all levels above 235. (when you will set correctly your contrast setting of your display)
See there why you need headroom: LG 2017 OLED Calibration Thread and Settings
If you expand to 0-255 the movie (RGB 0-255 / video playback application 0-255 / Display set to full range), you don't leave any headroom, you clip everything above 235, but colorspace conversion can have values outside video legal range, so it's a better idea to leave headroom, to prevent issues.
While above setting will be good for your movies from inside your software movie player, it will not be good for web/stuff, games which require PC Levels calibration, for that reason you will calibrate (without changing any of your PC settings) a different picture mode to your display, for PC level calibration.
BTW not all videocards can have accurate output to be used a software patch generation. To be sure that your video card is accurate, you have to compare it with your media player output... by displaying and measuring the same patterns. If you find aggrement in black/white levels, gamma, RGB balance and color gamut measurements, then you can use your notebook for patch generation. A lot of people skip that test, unfortunately. (see more details reading the ''4'' here