Hello, first post.
Long story short, I'm looking for a circuit that will take R, G and B signals and gamma correct them such that bright colors are no longer blooming and losing detail while dark colors don't just go straight to black. For more details...
My experience with electricity starts and ends with video game console modifications, but I've done a lot of that and strayed from the instructions a few times.
In January 2017 I started to research and build prototypes for an analog RGB to YPbPr encoder with the intention of getting my old video game consoles talking to my CRT with better clarity than S Video. I never wanted to just buy a converter that would do it for me, because I want to develop my own thing that will be smaller, take power from the console instead of a wall, and be more adjustable. I followed four different schematics I found online (and got terrible results with all of them) and I've most recently started working with a BA6592F. The picture I'm getting out of this thing is nearly perfect, minus some noise issues and something having to do with... impedance matching? But the most glaring fault of the thing, and what I'm trying to address right now, is that although I can make the overall picture brighter, darker, or more/less saturated, I can't fit both the dark and bright colors into my signal at once. If I make the whole image darker then I get good detail on bright images but dark colors simply display as black. If I brighten the whole image then bright colors all blend together but dark images are detailed. It's driving me nuts. This same problem happened to me using a transistor+resistor only design, so I am fairly certain it has nothing to do with the ba6592f. The only information I can find about this is from a very informative paper by Maxim Integrated ("Understanding Analog Video Signals") and all it really mentions about gamma modification is that "In analog, it takes the form of a non-linear amplifier where one of the gain resistors around an op-amp is replaced by a real or a piece-wise equivalent to a non-linear impedance. This is non-trivial in terms of design. Analog γ correctors are seldom accurate, and they require trimming adjustments. A side effect of γ modification is distortion." It also mentions that gamma correction should be done digitally but that is completely unacceptable for what I'm doing; my circuit needs to stay analog.
I learned how to make a voltage divider like two months ago, and how to use transistors like last month. I'm not going to figure out what kind of op amp I need to use or the resistor value it needs (or even how to wire this all) by myself. If anyone here has any idea what I should be doing, I'll be grateful. I'll even take search keywords; I really have no idea how to tackle this yet.
Long story short, I'm looking for a circuit that will take R, G and B signals and gamma correct them such that bright colors are no longer blooming and losing detail while dark colors don't just go straight to black. For more details...
My experience with electricity starts and ends with video game console modifications, but I've done a lot of that and strayed from the instructions a few times.
In January 2017 I started to research and build prototypes for an analog RGB to YPbPr encoder with the intention of getting my old video game consoles talking to my CRT with better clarity than S Video. I never wanted to just buy a converter that would do it for me, because I want to develop my own thing that will be smaller, take power from the console instead of a wall, and be more adjustable. I followed four different schematics I found online (and got terrible results with all of them) and I've most recently started working with a BA6592F. The picture I'm getting out of this thing is nearly perfect, minus some noise issues and something having to do with... impedance matching? But the most glaring fault of the thing, and what I'm trying to address right now, is that although I can make the overall picture brighter, darker, or more/less saturated, I can't fit both the dark and bright colors into my signal at once. If I make the whole image darker then I get good detail on bright images but dark colors simply display as black. If I brighten the whole image then bright colors all blend together but dark images are detailed. It's driving me nuts. This same problem happened to me using a transistor+resistor only design, so I am fairly certain it has nothing to do with the ba6592f. The only information I can find about this is from a very informative paper by Maxim Integrated ("Understanding Analog Video Signals") and all it really mentions about gamma modification is that "In analog, it takes the form of a non-linear amplifier where one of the gain resistors around an op-amp is replaced by a real or a piece-wise equivalent to a non-linear impedance. This is non-trivial in terms of design. Analog γ correctors are seldom accurate, and they require trimming adjustments. A side effect of γ modification is distortion." It also mentions that gamma correction should be done digitally but that is completely unacceptable for what I'm doing; my circuit needs to stay analog.
I learned how to make a voltage divider like two months ago, and how to use transistors like last month. I'm not going to figure out what kind of op amp I need to use or the resistor value it needs (or even how to wire this all) by myself. If anyone here has any idea what I should be doing, I'll be grateful. I'll even take search keywords; I really have no idea how to tackle this yet.