The latest version of NES Screen Tool has improved BMP import features. I’m going to give them a try. The BMP must be a color indexed, 16 color, or 256 color. I think 16 color works better.
I found this image somewhere on the internet. I reduced the image to 256×240.
Using GIMP, first I adjusted the levels, especially the midtones, so they will not wash out.
My first attempt, I darkened the background and then converted to NES color (I previously made a custom palette using the NES palette). Then, Image/Mode/Indexed, and chose the NES palette. Then I Image/Mode/RBG. Then I Image/Mode/Indexed, Optimize to 16 color. Here’s what we have…
Then, I imported to NES Screen Tool, with only ‘lossy’ checked. This is what I got.
Ugh. Not great. Try again. Took the Original Image (256×240), leveled, with a darkened background…
Image/Mode/Grayscale, then Image/Mode/RGB. Then I selected the Pencil Tool (or brush), and changed it’s mode to ‘color’ and selected a Orange color, and recolored the gray image like a duotone. (I also adjusted the levels again).
Now…Image/Mode/Indexed, chose NES palette. Image/Mode/RGB. Image/Mode/Indexed, optimized for 4 color. Image/Mode/RGB. Image/Mode/Indexed, optimized for 16 color. (The NES Screen Tool seems to do better if you have the final in 16 colors).
This is what the final version looks like in GIMP. Let’s import BMP from NES Screen Tool again (only ‘lossy’ checked)… (and I touched up some tiles in NES Screen Tool).
Much better.
Next time I’m going to import this as a background, compressed as an RLE file.
nesdoug 
I have been using GIMP to do NES sprites and thought it would be easy to import them to NES Screen tool maker…. but have not got the settings figured out I guess. Looks like I need to make the BMP color indexed, 16 color, or 256 color. I played with the save settings and adjusted several things but can’t get it to work yet, it will now import the file to NES Screen Tool Maker but only in one colour.
Will try a few more things because redoing them all is just…. so very time consuming.
Looking at your conversion of a photo to final GIMP/NES image… not bad, some work and it can be improved 40-50% in detail but you’re doing a good job.
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OK, followed your directions and it works fine, but my second fear is now you can only use 228 sprites to do a nametable…. oh NES and your limitations. That would be plenty for most instances but … hmmm just have to be more creative I guess. So much to learn it never ends.
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