On NTSC Video, Blue Blurring, Chroma Subsampling

NEOGEOman writes "Something I've been fascinated with for a long time is video signals. On my website I've spent over six years collecting video and other hacks for game consoles. I've recently put together the fourth revision of my video signal primer and it's expanded to six pages now, including strange subjects like chroma subsampling, horizontal colour resolution and rather interesting revelation: your eyes suck at blue."

Re:Obvious Physics

[Hard_Code]

I don't doubt that our eyes are less responsive to red and blue (I already knew that) but isn't the example sort of contrived? I mean, if I showed you a completely RED square, and then proceeded to remove both the RED and, say, BLUE color components, would that be proving anything? Obviously removing all the RED in a primarily RED picture is going to have more of an affect than removing any other color. The question is was the blue component in that picture significant to begin with (and in reverse deduction, is blue in the environment significant to begin with).

Nice Work NEOGEOman

[PostConsumerRecycled]

NEOGEOman, I just wanted to say gret job on the signal primer. I had always been a bit curious about video signals, though I had never looked into the subject. So I just wanted to to thank you for making an easy to understand document that covered everything I wanted to know (and more).

Re:Obvious Physics

[NEOGEOman]

OK, so you're saying our eyes don't suck at blue, or that they suck for different reasons? The end result as I see it is exactly the same - we still perceive very low resolution in blues, and we can reduce the detail in an image's blue channel without a noticable drop in image quality. This is proven through the pictures I provided. Is there more to the story? There sure as hell is! Am I the world's leading comprehensive source for Eyes+Blue information? Nope, nor do I claim to be.

What you say is fascinating, but beyond the scope of my tiny little primer which aimed to prove one point (And I think succeeded). As for the chart I linked to, you might be best to take up your crusade with them. ;)

Re:Digital camera invalidates the demonstration

[NEOGEOman]

Alright, I'll tell you exactly that. I used a digital camera, and reduced the image to 25% using an interpolated scaling to create an image much closer to 'balanced' than a raw digital image would be. By scaling it this way the image was resampled to the new size by combining and averaging the pixels, negating any effect the camera's CCD had.

According to the histogram the colours are very nearly the same but for some variation in the highs.

What you say is irrelevant for the discussion, really, because a digital camera also uses JPG compression which, as we've discussed, creates a high-res green and low-res red + blue image. That's the other reason I resampled it, it negates the JPG effects and creates a (very lovely) new image without effects from the CCD or JPG compression.

Does that satisfy you?