Do I need color correction? DVD and Blu-Ray colors are so different

[killerteengohan]

I'm used to watching my DVD's but I recently got a Blu-Ray set for the same thing.

They look so different color wise though and I think I prefer the DVD colors or closer to them. I think the Blu-Ray looks a little more yellowish tinted.

Can anyone help me get closer to the DVD colors in avisynth? It doesn't have to be exact but a bit closer would be nice. I'm not too good with color editing/correction or reading those graphs made in avisynth I've seen posted before elsewhere.

I have uploaded a couple images with a comparison of the 2.

[killerteengohan]

I thought I would try a few Hue/Sat changes in tweak but it didn't seem to work out too well. A little more added saturation looked nice to me, but didn't affect the overall colors too much.

Can I reduce just the yellow color/tint a little bit perhaps, maybe make it a little more red or blue?


I tried out something called histogram and colorYUV but I don't fully get what to look for in the histogram.


ColorYUV(off_u=2) looks a little closer to me, but still not what I was hoping for.


I tried adding a bit of saturation as well, then lessened it more to about 1.05, but there's these line breaks appearing in the white parts of the histogram when saturation is added. Are those lines a bad thing?

Heres what I'm talking about with the lines. Take a look at the histogram.

[killerteengohan]

Whats confusing me is, the DVD and Blu-Ray histograms look close to the same to me when it comes to being in the middle, so why are the colors looking so different. And whats with the line breaks in the histogram when I add saturation or brightness/contrast? Are those line breaks in the histogram a bad thing? (Example is just above)

[jagabo]

About all you can tell from those U and V histograms is the white balance (center) and the saturation (how far the extend left and right).

I'll look the issue more tomorrow but I don't think you're going to find an easy solution in AviSynth.

[theewizard]

i'm not sure what you mean :used to watching DVDs

do you mean the DVDs look different when played on the BD player ?

do you mean you are playing the files on the BD, files that were used to create the DVDs

either way it comes back to it being the output of the BD player, not the DVD or file

unless you want to re-do ALL your files
you need to adjust the settings on the TV, unless the BD player has color adjust settings

[killerteengohan]

i'm not sure what you mean :used to watching DVDs

As in I've watched the DVD's and are used to their colors and how things look. For example, what I am used to seeing as a purplish color on the DVD's is now showing up as Grayish or so on the Blu-Rays video.

either way it comes back to it being the output of the BD player, not the DVD or file

unless you want to re-do ALL your files
you need to adjust the settings on the TV, unless the BD player has color adjust settings

The TV or BD player has nothing to with with what I'm wanting to do.

I want rip and compress my blu-rays for watching on my computer, phone or tablets. I'm trying to get the video colors to look similar to the DVD's video colors in the encodes, that's all.

[killerteengohan]

About all you can tell from those U and V histograms is the white balance (center) and the saturation (how far the extend left and right).

I'll look the issue more tomorrow but I don't think you're going to find an easy solution in AviSynth.

Thanks jagabo, I will check back tomorrow. If you need anything else to help with it, let me know.

[Cornucopia]

Those histo lines likely have to do with banding/posterization due to lack of dithering when doing high bit->normal bit calcs in your scripts/tools.

Maybe your player isn't properly using the appropriate colorspace for the material (601 for SD, 709 for HD).

Scott

[jagabo]

Though it's a possible issue, the differences are far more than rec.601 vs rec.709. And they're different in different shots. Each scene was tuned to get the colors they wanted.

[KarMa]

I have come to understand that those avisynth previews in programs like Megui and Avspmod, might preview YUV content in rec.601. No matter if it's HD or SD.

https://forum.videohelp.com/threads/380081-AMD-Polaris-%28Radeon-RX-4xx%29-H265-Encodin...=1#post2470677

[jagabo]

Yes, that's quite common. Or sometimes the inverse -- everything is decoded with rec.709. But the difference between rec.601 and rec.709 is barely noticeable. And it doesn't effect greys. The third of killer's sample images shows a very distinct red shift in white shirts of the SD image.

[awgie]

I didn't compare all four sample images, but in image 4, the DVD image is much darker overall, as opposed to the difference in image #3. However, as to the colour shift, the relationship of red to green to blue is similar for each image. (i.e. for the area I examined, in image #3 the RGB ratio of DVD:BD was .94/.78/.86, and in image #4 it was .76/.63/.69) But since there is such a marked difference in how much the overall brightness changes, like jagabo said, I don't think you're going to find an easy solution.

My guess is that the videos were re-mastered, so to speak, for the Blu-Ray release, to get the image to look the way it was originally intended, so different scenes received different treatment. Maybe it's just me, but I think the Blu-Ray images look a lot better. But if you really prefer the way the DVD looks, even if it is just because that's what you're used to, I would just use the DVD files for encoding the videos.

[jagabo]

As was pointed out, different shots need different adjustments. But if you really want sickly colors/brightness like the old DVD this is a compromise setting that gets in the ballpark:

# YUV source
ConvertToRGB(matrix="rec709")
hd = hd.RGBAdjust(r=1.00, g=0.83, b=0.93) # reduce greens and blues

ConvertToYV12(matrix="rec709") # back to YUV
hd = hd.ColorYUV(gain_y=20, off_y=15, gamma_y=-50) # gamma adjustment, gain and offset to match
hd = hd.Tweak(hue=-45).ColorYUV(cont_u=0, cont_v=-80).Tweak(hue=45) # saturation adjustment

[jagabo]

ColourLike() attempts to match the levels/colors of one video to another. It works reasonably well for individual frames of your screen caps. But not when trying to correct more than one. Ie, the fix for one pair of images doesn't work for the others. Still, running it over the entire video might give you an OK compromise.

[killerteengohan]

Someone else who wanted to do the same thing as me seems to have done pretty good at it. I don't have a way to ask them how they did it though. Here's a screenshot comparison for 2 images.

http://screenshotcomparison.com/comparison/194643/picture:1

http://screenshotcomparison.com/comparison/194645/picture:1

[jagabo]

To make the mouseover image look like the other image simply increase the red and green channels by 10 percent.

RGBAdjust(r=1.1, g=1.1)

[killerteengohan]

Thanks Jagabo, it looks fine to me. I will play around with that some.


I have been adjusting saturation like this.

smoothtweak(saturation=1.00, dither=-1, interp=0, limiter=true)


I read the limiter clamps luma and chroma output to 16-235 for luma & 16-240 for chroma. Is using the limiter a bad thing? Is it better to make it false all the time?

Wouldn't always having things at 0-255 be better?

[jagabo]

Almost all consumer distribution format and playback devices use and expect limited range YUV. A long time ago some of them would display video incorrectly if the YUV data went outside the specified range. For example brights above 235 might show up as black instead of white. Over saturated purples might show up as green. Most devices don't have that problem anymore but it's safer to limit the levels before your final encode.

You should also note that not all combinations of YUV map to valid RGB colors (what shows up on the screen) even if each individual component is within its respective range. For example, when Y=16 (black) the only valid values of U and V are 128. If you look at the RGB cube inside the YUV cube you'll see that only about 1/6 of the YUV cube maps to valid RGB colors:


from: https://software.intel.com/en-us/node/503873

I made a quick/dirty script that highlights any parts of your image that fall outside that legal area with red (or an optionally specified color):
https://forum.videohelp.com/threads/360935-Capturing-Correct-Chroma-and-Hue-Levels-From...=1#post2289672
Earlier in that thread there's a more accurate script but it's very slow to load up. And it is somewhat the opposite of my script in that it shows the bad areas as picture and the rest of the frame as black.

Don't worry about little bits of illegal colors (like in the black lines of cartoons, oversharpening halos, etc.) Just watch out for big areas of illegal colors.