I’ve been reading and experimenting with ciecamenh and made a list of possible changes to the user interface that I think might make the module more useable for general cases, and also perhaps easier to use:
My apologies in advance, it’s a long list!
- An easy way to reset sliders to their default value:
Some of the sliders have a checkbox, some have a “reset” arrow, some have both, and some have neither. Checking the box returns the slider to the default value and also disables using the slider until the box is unchecked.
I think it might be more convenient if none of the sliders had the box, and all the sliders had a “reset” arrow that would reset the slider to the default value.
It also might be nice to have a “master” reset arrow or box that would allow to reset everything at once to the default settings. This would allow people who are experimenting with CIECAM02 to get back to the original settings without having to guess or do a lot of clicking. Perhaps a “per submodule” box would also be nice. This way, for example, the user could leave the “Image Adjustments” sliders as set by the user, while having the option to reset the Scene and Viewing sliders.
- Conserving screen real estate:
With the extra sliders enabled in the Scene Conditions, it would be nice to have the option to “fold up” the individual submodules, to allow the contents of the remaining submodule(s) to be visible without scrolling.
- Scale of Scene/Input luminosity vs Viewing/Output luminosity:
The current “scene luminosity” scale goes to 16384 (2^14). The current “viewing luminosity” scale goes to 1000.0.
For the particular use of preparing images for display in a room with normal or dim room lighting, these scales cover what users would likely need.
But for other uses - such as when a user really only wants to use the “Image Adjustments” module, or if a user wants to make “aesthetic” adjustments via a CIECAM02 chromatic adaptation - it would be nice to allow the viewing/output luminosity to go just as high as the scene/input luminosity. This would allow the user to accurately set the Scene/Input luminosity, and then also be able to set the Viewing/Output luminosity to match.
- “luminosity” vs “luminance”:
A lot of image editors use “luminosity” to refer to various units of measure connected with “how bright/light” something is. But technically speaking, “luminosity” refers to the energy output of astronomical objects (https://en.wikipedia.org/wiki/Luminosity). It seems to me that when image editors use accurate terminology, users have an opportunity to learn “correct stuff” - imagine if a user tries to look “CIECAM02 luminosity” up in a book or journal or on the internet.
It took me awhile (and a fair amount of reading) to figure this out, but RT’s “Scene luminosity” and “Viewing luminosity” refer to absolute luminance, out there in the real world. So for these sliders it would be nice if “luminosity” could be replaced with something like “luminance (abs.)” or “absolute luminance”.
Yb is relative luminance (more reading) and so is a percentage. I think it might be helpful to users who want to “dig beneath the surface” of the RT CIECAM module if Yb sliders show a percent sign, and maybe the labels could mention relative luminance, with an on-hover tool-tip that explains a bit about what Yb is - with unfamiliar terms and concepts, tool-tips are greatly appreciated!
- Access to Scene Yb, and sliders for Scene and Viewing Yb:
Currently Scene Yb luminance is only available under Preferences/Color Management. It’s hard-coded to Yb=18/L=50, or else to “Automatic” (there is no slider to set some other value), and the comments say the image must be reloaded before changes take effect.
Could Scene Yb be made available from the CIECAM02 module, with a slider that goes from 0% to 100%? And could the Viewing Yb scale also go from 0% to 100%? Of course the extremes are unlikely and even unuseable! But including the extremes allows the user to experiment freely.
Currently the surround option for Scene is limited to checking or not checking the “dark” box, which doesn’t seem to exactly equate to the Viewing option of “Dim” or “Dark”. It might be nice to have the same options for Surround in both Scene and Viewing.
- Access to LCH or JCH color picker values:
The RT color picker reads out LAB and RGB, but ideally needs LCH - or even better JCH - when used in conjunction with the CIECAM02 module.
For example, I was trying to use the RT CIECAM02 module to move the JCH Hue of a photograph of the moon to something like 105, and the only way currently this can be done is via color picking combined with using something like ArgyllCMS xicclu at the command line, and then making compensatory adjustments, color pick again, etc, until reaching the desired Hue.
LCH is not a substitute for JCH as the Hue angles don’t exactly line up. But LCH is probably easier to put in the RT color picker than JCH, and also probably “close enough” for most uses, though down around Hue 270 things diverge quite a lot, and I have no idea what happens when the full CIECAM color adaptation model is being used. In an ICC profile color-managed editing application, I suspect “everything relative to D50/L=50” is the best thing for a color picker.
- Temp/tint and also presets for choosing the white points:
Temperature/tint allows for a great deal of user control when setting and modifying the Scene/Input and Viewing/Output white points. I think it might be useful to also have access to presets (sort of like in the Colors/White balance module), including perhaps these presets:
plus whatever is appropriate for known display devices such as projectors.