Hey,
would it be possible to add support for some gleba-specific sprites? I'm having a really hard time identifying Yumako trees for example, as the fruits just blend into the background, or telling from the map screen what's water and what's not (not sure if that part is intended though)

Thanks for the suggestion! Are there other sprites you have trouble with? I must admit I still haven't built a Gleba factory yet, so I have no personal experience to draw from.

If the Yumako fruits are the only difficulty, then it should be simple to add a color picker that would adjust the color of the fruits.

or telling from the map screen what's water and what's not (not sure if that part is intended though)

This is an interesting request, as it is actually possible to modify the color that tiles appear on the map. (For example https://github.com/wube/factorio-data/blob/2365bf12bf9ef4cc1c6cd50f430c9f88b298af63/space-age/prototypes/tile/tiles-gleba.lua#L128). The trick is figuring out how to fix it. There are 45 different tile types on Gleba, and exposing a color setting for each of them would be completely impractical. Maybe you are trying to say you only care about tiles that players can't walk on? In that case, "gleba-deep-lake" is the only Gleba tile that matches that, so I could add a color picker for that tile's map color.

I'm also just beginning on Gleba, so for now the most noticable thing were the Yumako fruits. I took a look at the files and it seems like there's actually a "normal" a "harvest" sprite, I assume these are picked based on whether the tree is ripe for picking? Not like I can tell lmao.

45 different tiles is definitely not feasable, but the deep lake is not a problem, at least for me. What was more difficult is distinguishing the buildable terrain for the harvestable plants from the marshes that have the same color, but turning off the new "Additional terrain effects" graphics setting in 2.0.21 actually helped in that regard. The settings is meant for performance reasons but also changes how buildable terrain is rendered.
I think where my original request came from, was that I took to the map screen for help, since I couldn't tell what was water and what wasn't, but that didn't do much. I actually got used to how the map looks now and can tell things apart better after disabling the new setting.

I have finished Gleba on my save, so I feel like I can speak from experience now.

for now the most noticable thing were the Yumako fruits. I took a look at the files and it seems like there's actually a "normal" a "harvest" sprite, I assume these are picked based on whether the tree is ripe for picking? Not like I can tell lmao.

I agree. I'm not sure why they have different sprites; maybe they are different colors. I'll need to ask a normal color vision friend to confirm that. If that is the case, some sort of adjustment would make sense. If not, then I'm not sure what adjustments would be needed.

As for water, that has frustrated me quite a bit as well. I have ended up shift clicking any placement action just in case what I thought was land was actually water. I think normal color vision struggles with that as well, but again I will check with a friend.

In any case, suggestions on specifically what to change would be helpful. The mod doesn't modify many sprites because I haven't thought of good modifications to do that would be helpful, other than the underground belts.

I think if a color picker for the sprites isn't possible, it would be good to have an alternative sprite for the Yumakos with a higher contrast to the surroundings, like a dark blue or black. I'm not sure it matters too much whether it's the normal or the harvest sprite, the agricultural towers take care of that anyway. Maybe only to see at a glance if an entire tree patch is not fully grown, to tell at a glance when expansion is needed. An idea I just had is maybe one alternative that just changes the fruit to high contrast and one that changes the entire tree's color, then we don't have to figure out which different fruit shades would work for most color blindnesses.
As for the water I can really recommend turning the "Additional terrain effects" graphics setting again, it worked wonders for me.

I dug into the API around trees. It's pretty interesting actually; the devs just extended the Nauvis Tree prototype to create a Plant that grows instead of dies. This is why, while there are multiple sprites per image file, they are all the same size, as they are used as variations instead of animations.

It took me a while to figure out what the "normal" images are used for (as the docs do not mention that), but it seems they are used for animating the leaves, so the name likely references normal in terms of geometry. "Leaves" in the API meaning of the word, as the files are called "harvest", but they are registered as leaves.

Anyway, the TreeVariation does support color tinting, but the default trees already have that, used for color variation on the fruits (see the prototypes):

local function minor_tints() -- Only for leaves where most if the colour is baked in.

So I added a way to customize that. Due to how the tinting works, some of the color dynamic range is lost, but a more uniform color for the fruits is probably helpful anyway.

Long story short, I added this in v2.3.0. Let me know how it works for you.

Holy shit dude thank you so much, this is miles better. There's so many trees all around that I never saw before! https://i.imgur.com/pIFCR5P.jpeg

You picked the same color as me, nice! Glad it works for you :)