A question to chew on - I'm curious what the proper workflow "should" be:
Base Setup:
1. LED Lights are setup in specific areas to illuminate the painting from the left and right to eliminate glare and reflections so these should never move. Currently each light is 2ft in front of the paintng but 7ft to the left and right. This gives me great lighting with no glare on the weave of the canvas.
2. Camera Position is placed to encompass the entire piece so this won't change. Most of my paintings are 40" tall.
3. Easel is located at specific location with a black cloth behind the easel so this won't change.
Workflow ?'s:
1. With camera located in specific location as noted above: With proper exposure take picture of color card on the easel without painting, just the card.
2. Create ICC profile making sure LAB colors are as accurate as possible.
3. Place painting on easel (no color card), expose as needed then take picture. (Exposure settings may be different than settings required for color card).
Question:
Since the "exposure" of the card and the painting should be nearly equal would we expect the ICC profile to work accurately?
Because:
If the card is placed on the painting and the exposure is adjusted to get a good exposure of the painting then it's possible the card will be underexposed or overexposed depending on how bright the overall color of the painting is.. Yellow painting vs Brown painting. Correct? If this is true then I can see where the ICC won't work.
Hmmmmm.
I'm getting quotes for basiccolor and they recommended a training course but didn't give me a price. Any thoughts on what this encompasses?
ks
I should be very clear that I'm not a color or profile expert. I'm always learning and I find it thoroughly interesting. I do make profiles for certain product shots where color is important but it's only part of the equation and in general, I use Capture One profiles, certainly for my Phase gear. There are far, far more qualified people on this forum who can speak with authority on such things. I'm merely a garden variety schmuck. I can only offer my own experiences and hopefully there are nuggets worth something
. With that...
What's your end output? I know you sent the painting image in question to a magazine for a cover recently. Is that typical? Do you send them to social platforms and such? The question is really, how accurate do you want your colors? Do they have to look good and seem right or... do they absolutely have to be spot on? The latter can be a fair amount more work, in my experience. Profiles are part of the story and help, but the Capture One color management tools are another part (or whatever your processor of choice happens to be). If the answer is the former ( look good and seem right ), I'd really recommend getting a nicely exposed shot of your painting and experimenting with non-IQ180 profiles and working with the excellent color management tools in C1 to tweak as needed. Really, if you get a nicely exposed shot, you can probably tweak the image directly from the IQ180 profiles themselves. The included ICC profiles in C1 are designed to be much more flexible than an in-situ profile. They work in a variety of lighting situations and lens choices.
Making a generalized camera profile is possible similar to what you find in C1 or other tools, but it's (way) beyond my level, for sure. There's a really in-depth article by the developer of Lumariver
here which is super interesting and very technical. But basically, what we're doing with a tool like Basiccolor or the software from Xrite is we're building an in-situ profile. It works for the specific camera, the lens, the lighting, the scene and so forth. Well exposed, even illumination on the card of choice is very important, I've found. I would trade slightly underexposed for making sure it was evenly illuminated. If it's a little underexposed but still evenly lit, you can tweak the levels so that the L* value is 95-ish on, say A1 or E5 on the ColorChecker SG. Don't change the L*value with exposure as it's very non-linear. So levels work great. Basically, you want the white point of A1 or E5, say, to be in the 95 range. The steps I use (YMMV) typically are:
* Evenly illuminate the target color card with how you want to illuminate the painting and get a good exposure. Avoid excessive under exposure. Optimally, keep the image plane/sensor parallel to the card, even if the desired targeted image - say the painting - are at a different angle (on an easel).
* For the "Base Characteristics" ICC profile, I use Effects->No color correction.
* For the curve, use whatever curve you tend to apply. Capture One's default curve is "Film Standard". If you see "Auto" for curve, that's what it's using. If you use Linear Scientific or Linear Response, choose those for the curve.
* Set the white balance - I use F5 on the ColorChecker SG.
* Set the white point luminance. 95-ish for A1, E5, etc on the ColorChecker SG. Use levels or curves - not exposure.
The white point luminance is important because you want a profile that doesn't brighten or darken your image. So getting the patches A1, E5, 10N mostly evenly illuminated and close to their L*value (95-ish for the ColoChecker SG for example) is awesome. Again, use levels or linear curve vs C1 exposure changes. Make sure your monitor is calibrated if it isn't. Angle of illumination is important, too. When you're measuring delta Es, you're basing that on an assumed angle of illumination and things like D50/D65 color temps.
As far as basiccolor training - basic BasicColor isn't too difficult when you're using known targets and following the above ideas. The Cultural Heritage folks at Digital Transitions have a number of YouTube videos that can get you going.
https://www.youtube.com/@DigitalTransitions/search?query=basiccolor shows their current list.
