What Is A Raw Image?The attachment contains the executable that was compiled using mingw32 on a 64 bit Windows 10 PC. The PNG library that I used is LodePng, the source is in the download.
A raw image, whether it be a file or an image in memory, is simply pixel data. There is no extra information like width, height, name, end of line... Absolutely nothing, just pixel data. If you have an image that is raw and the resolution is 1080x1920 and you are using a typical RGB24 or BGR24 (like the ones used here), then your exact filesize or size in memory will be 1080x1920x3! We use 3 here because there is one byte for the R or red component, one for the G (green), and one for the B(blue).
What Is A Run Length Encoded Image?
A run length image encoding uses a count ;usually a single byte (char), 2 bytes (short int), or 4 bytes (long int); and then the pixel components. So instead of writing out 300 bytes of '0's to make a line of 100 black pixels. Black is RGB(0,0,0). You could encode this as 100, 0, 0, 0. And only use 4 bytes of data to get the exact same image as the 300 byte raw image. All the run length encoding I've found, except the Motorola style which is a little different, use a run length encoding that is pixel-oriented like this.
Now I've found this new one and it is a byte-oriented run length encoding. This is for runs of bytes, not pixels. You may think, well whats the big deal? When you add a little area of color, you increase the run length encoded image in you logo.bin immensely! You use 6 bytes per pixel if there aren't any runs of color data. If you had an image that was a 1080x1920 black image with a 25 pixel horizontal line in the middle. The encoder would be doing runs of black data efficiently until it reached the red area.
.....0 255 0 255 0 255 0 255 0 255 0 133 /// we've reached the top left corner of the red line /// 13 1 30 1 255 1 // << that was just one red pixel!! in bgr color order (13, 30, 255) <<// And it keeps going through the rest of the red pixels on that line using 6 bytes per pixel, which is the opposite of compression. Before reaching the red line the encoding was decoding to 255 zeros over and over, until finally 133 zeros. 255 zeros is 85 black pixels stored in just 2 bytes!
This type of encoding is ONLY good for grey scale images. It is not good with color, but it still will handle color of course. In grey scale, the Red, Blue, and Green data components are always the same values. All the way from black (0,0,0) to white (255, 255, 255); including every shade of grey in between>>>(1,1,1) (2,2,2) (3,3,3)....(243, 243, 243) (254, 254, 254)<<<
One other difference in this method of run length encoding is that the color byte is before the count, which is backwards from all of the other methods.
Big thanks to @RajGopi for sharing his logo.bin with me and requesting this mod, and testing it as well!
To use the OnePlus 5T Logo Injector:
Decode your logo.bin:
OP5tLogo -i logo.bin -d
Note:Inject the image(s) back in to the logo.bin:
Your original "logo.bin" file is never changed, it is just read. If the file you try to load isn't a logo.bin file, or a different style, then the program will tell you and exit.
OP5tLogo -i logo.bin -j fhd_oppo fhd_at
OP5tLogo -i logo.bin -l
OP5tLogo -i logo.bin -L
OP5tLogo -i logo.bin -d -s
OP5tLogo -i logo.bin -j image_name -s
Note:The size of your modified.logo.bin will displayed along with the original size, if everything went good. The 'splash' partition is 16 MB on the OnePlus 5T. If you use too much color on too many of the images you will easily go over 16 MB. The program will tell you and delete the "modified.logo.bin" that was created. If for some strange reason you would like to keep it, use the "-B" flag on the command.
You can put as many names after "-j" as you want, and it's not case sensitive. You also don't have to put the whole name. If you just put "-j fhd" every image in the logo.bin that starts with "fhd" will be injected. There has to be a PNG with the name in the directory though
The last step is to flash the modified logo file via fastboot with the command
fastboot flash LOGO modified.logo.bin
Use this at your own risk.
Always make backups.