chelseagraham
commented
7 months ago Another program has said
For herbarium imaging you will probably find that its unnecessary to colour manage everyday in order to get good results (its very time consuming so there is a trade-off to be had), but that there are a few key things within the capture software settings that will probably greatly improve your golden thread results with a bit of experimentation with settings.
you want to try to get the colour as good as possible as you only really want to be doing this once! Depending on the number of specimens to be imaged, there is a balance to be had though, as colour calibration can be time consuming so we tend to use the Golde thread to analyse the stations on setup and periodically to monitor the stations, but it isn’t feasible (and probably unnecessary) to calibrate every session/daily, as we find that we can get fairly good colour fidelity without this. Thanks for forwarding your manual, I will read this properly next week but I can see from a quick scan that you use DeltaE for analysis of the targets, we use the GoldenThread software that comes with the GoldenThread targets but they are essentially measuring the same parameters and the targets are also very similar.
The lighting will definitely have an impact on the colour too, but something you could try is an LCC profile (this may be covered somewhere else in your manual so apologies if so!) you may also find that the curve being used may need adjusting? I am not familiar with Phocus software but I will take a look! Another thing to keep in mind is the 3D nature of the herbarium material and that it will behave slightly differently under the lighting than paintings/books (getting double shadows etc). We also check for light uniformity using a white board as you do, and also use this for creating LCC profiles.
As you are using CaptureOne I would strongly recommend using the Linear Response curve under the Base Characteristics if you aren’t already, as this will should improve the colour results (you may need to up the lighting a little). If you’re not already using this, I would try it before going down the LCC route.
LCC is fairly easy to set up (just need a clean white board) and can be useful if your lighting and camera setup are strictly maintained in the same location.
Gomismis
An analogous program responded with the following when asked how exactly they calibrate at the beginning of each session what post-processing they carry out
Our colour management is quite basic, in part because with preserved plants the original colour isn't maintained. Every specimen has a golden thread colour chart included so that if we wanted to we could do more complex colour correction at a point in the future.
At the start of the session we take a test shot and check the white balance by hovering over patch 13 (3rd darkest grey patch)to check the RGB values don't deviate by more than 1 or 2 values. I created a custom white balance using patch 13 and embedded it in a custom-made style (collection of settings applied to each image) used in Capture One Pro, which we use for tethered imaging.
To check image exposure we hover over the white value in the test shot to make sure it's ~ 230 (i.e. not over exposed). We used to also check the black patch too (when using an x-rite chart with our older set-up which used Bowens fluorescent tube continuous lighting) ensuring it was around 30. When we switched to LED lightboxes the LEDs didn't render the black patch correctly (they weren't photography LEDS, we now have setups with LEDS appropriate for photography) so we couldn't use it as a reference.
We also correct for light fall off as our lightbox is open at one side by producing a Lens Cast Calibration setting using a LCC plate (The DTCH Digitization Workflows Guide has a good section on setting this up and creating bespoke ICC Profiles).
We use Adobe RBG colour space for both RAWS and TIFFS and Capture One's default ICC profile and film curve for the camera model we have. We do not own any colour management software either for bespoke ICC profile creation or for colour QA.