What are color bars and why doesn't my camera have them?
- Thread starter masterdp
- Start date
They are very much a pro thing as in, and one you'll definitely want to learn about and use when possible. As I understand it, in the HD world (I still have an SD cam and monitor, believe it or not), many monitors calibrate to color spaces (601 vs 709) instead of the bars. So, you set your monitor to the proper color space, and BAM, you know the colors/contrast you're seeing on the monitor are what the camera is "really" seeng. But some HD monitors don't calibrate to color spaces--that's where color bars come in. You can find tutorials online about how to calibrate your monitor to color bars (the process varies slightly depending on which bars the camera displays--plain ol' NTSC, full frame, ARIB, etc.), but it involves twiddling with the contrast, chroma, etc. knobs on your monitor til this thing matches up with that thing. Again, the idea is that once the monitor is calibrated to that cam's specific bars, you're seeing an image on the monitor accurate to what the camera is really shooting, as opposed to judging color/contrast off the viewfinder. Unfortunately, the DSLRs don't generate bars. Some have recommended putting a still of color bars on a card and playing it back through the monitor. . .to me this seems to make it calibrate really dark, i.e., something gets messed up in the translation from card/cam/monitor. Maybe someone can do some math and figure out how to compensate so that a color bar still on a card sends out proper luminance values to calibrate the monitor to. I've been using my XL2 as a color bar generator. Not a perfect solution, but better than calibrating to nothing.
sandisfield
Active member
Aren't there thousands of people using DSLR's to shoot video with? I know I've seen photographs online of DP's using DSLR's with monitors. I'm blown away that not a single person is shooting with a DSLR and a calibrated monitor. I guess I shouldn't be surprised - I've heard of lots of people putting mics on their cameras and trying to shoot dialogue scenes with no Production Mixer, so, live and learn I guess.
Matt Gottshalk
Resident Preditor
you can load a jpg image of color bars on to your cf/sd card, as long as it conforms to the image naming conventions of the images the camera makes.
Yes, but in my opinion (ive tried it), it comes out too dark causing you to calibrate the monitor too dark, negating the accuracy of the image. I suppose you could argue that overlighting could be graded darker whereas underlighting would give you noise when you brightened the image in post, but if its accuracy youre after then irs no good.
sandisfield
Active member
I still can't get over the idea that no one shoots with a calibrated monitor. I see pictures of Philip Bloom with DSLR's with monitors. I had no idea it was all BS. I fell for it and purchased a $1400 monitor I don't need.
I'm still a hobbyist really, but as I understand it most of the 'professional' monitors are already well calibrated from the factory. Also, as far as I understand, Color bars will only give you a basic calibration - a precise calibration will need to be done with a color meter and software with extensive manual adjustment based on data.
My monitor is relatively well calibrated, in terms of eyes-only DIY calibration. I changed the input from the DSLR on-board screen to the external monitor continuously, with adjustments, until it I got it to match. It works for what I need it for.
Barry_Green
Moderator
Monitor calibration isn't something that gets done once. It's something that has to be done each and every time you put the monitor in a new prevailing-light scenario. Go outside, re-calibrate the monitor. Move indoors, calibrate the monitor. It's about making sure that the monitor is displaying the image accurately so that you can trust it.
M. Gilden
Canon DSLR Moderator
I feel like I suggested this ages ago... or maybe that was a conversation I had in my head.
I joked once that all you really need is an image of the color bars on your storage card. Playback the image, and calibrate the monitor. How hard could that be? And if someone is going to complain about jpeg color shifting, etc, fine- so save it in RAW or something. To be honest, I never calibrated monitors on my full sized cameras so maybe I'm just not understanding something here.
Having the feature built in to ML would be great, though!
Barry_Green
Moderator
But even then, you're not really guaranteeing anything. How accurate is the HDMI output on your camera, for example? On the GH2 I can tell you, it just plain isn't. The monitor output doesn't match what the recording is actually delivering.
Simple fact is, if you're worried about precise monitor calibration, you should be using a camera that can accurately output color bars. And if you have a camera that can't accurately output color bars, you probably shouldn't stress too much about precise monitor calibration anyway.
If you can use an image (or even better, generate an image with code) you'd need to test the output with a vectorscope and waveform. A vectorscope such at the one below will let you know that the color bars are accurate and can be depended upon for calibration. If I'm not mistaken, a1ex, you use a SmallHD - I don't think it has vectorscopes.
I feel like I suggested this ages ago... or maybe that was a conversation I had in my head.
I joked once that all you really need is an image of the color bars on your storage card. Playback the image, and calibrate the monitor. How hard could that be? And if someone is going to complain about jpeg color shifting, etc, fine- so save it in RAW or something. To be honest, I never calibrated monitors on my full sized cameras so maybe I'm just not understanding something here.
Having the feature built in to ML would be great, though!
Yeah, I've read numerous times that you can't use an image. Not sure if the lack of compression would change that.
From Wikipedia (http://en.wikipedia.org/wiki/SMPTE_color_bars):