Step 3: Formatting
The first step in editing the image is to load it into GiMP and change two things. First, add an Alpha Layer. This lets you have the transparency where the empty space around the image will simply be whatever is on the map. To do this, you go to the menu Layers -> Transparency -> Add Alpha Channel.
- What could I possibly be working on here? I'm sure it's nothing...
- AddAlpha01.jpg (153.28 KiB) Viewed 1313 times
Additionally, to keep your proportions intact, you need to adjust the canvas size of the image. This allows you to have the image be square, even though you may have a tall full body image where your character is standing up straight and it won't try to compress you the wrong way. This is pretty straightforward, you go to Image -> Canvas Size and then set the Width and Height equal to the same number (picking the larger of the two so you don't accidentally crop the image). Make sure to hit the "Center" button to keep the image centered, or you'll always be slightly lopsided.
- We have to go deeper...
- CanvasSize.jpg (202.13 KiB) Viewed 1313 times
Assuming you've done this in the right order, you'll have some gray checkerboard on the sides of the image, that's the alpha layer. Once you've done that, it's time to get to the most important part, deleting shit!
Step 4: Deleting all that bullshit you don't want to see.
So there's a bunch of tools in this program, but you're only ever going to need a handful for stuff like this. There's the crop tool, the magic wand, and the lasso. The crop tool looks like an exacto knife, the magic wand looks like a motherfucking magic wand, and the lasso tool looks like a lasso. Or a speech bubble if you need new glasses. The magic wand will do most of what we want here. If you've got a white background to get rid of, simply select a place in the white background with the magic wand tool, it will be highlighted, and then...you delete it. By hitting the delete key. It will be replaced with gray checkerboard and then you can EXPORT (not save, saving saves it as a GiMP file with all the layers intact. Not a bad thing, but it won't upload well) it as a *.GIF or *.PNG (PNG is better, usually) and then upload it to Roll20. Congratulations, you're done. You may need to select a few white spaces if the image doesn't have them all in the same continuous patch, but it's a simple enough fix.
For images with backgrounds, well...that's an issue.
Let's look at the headshot from before. That has a relatively monotone background, but it's still in color. The magic wand has various settings that let it select similar colors with a degree of similarity, but you don't want it to be too broad or it will take chunks out of the parts of the image you do want to keep. This takes some experimentation (and a lot of CTRL-Z undos), or you can use the lasso selection tool, which lets you draw what you want to select. That requires more work and precision, but is sometimes the only way you can get the definition you need to extract the details without taking them out pixel by pixel.
- MagicWand.jpg (253.89 KiB) Viewed 1313 times
Threshold is the biggest thing you'll need to adjust for the magic wand tool. Too high a threshold and it selects basically everything, too low and it only selects a few pixels. Since the background in this image is very close to the armor and the hair of the character in question, the threshold has to be low to avoid taking out chunks of his hair and head. You may also note that there are a few pixels not selected on the selected area on the left side. That will happen, and usually when the image is shrunk down it's difficult to notice those dots, but if you want to get rid of them you can just use the lasso tool and draw around them to select them, then delete them as usual. Since most of these images are going to be shrunk down to the 100x100 range or less, you can get away with small imperfections most of the time.
Step 5: Export (Save) and Upload
Once you've got the image cleared up, you will want to save it, as mentioned above, by exporting it into PNG or GIF format. I recommend PNG, but your mileage may vary. JPG files WILL NOT read the transparent layer, and so all that work will be automatically undone and it will be white once more. Saving the file as a GiMP project is not a terrible idea in case you need to go back to it, but it won't upload like that.
To upload it to Roll20, simply drag the image onto the board and go from there, or if you're a player, give the file to the GM and they will do it. I'll handle the other parts of Roll20 tricks in another thread elsewhere.
