some Indexed BMP Images look corrupted

[carson-coder]

CircuitPython version

Adafruit CircuitPython 9.0.0-alpha.6 on 2023-12-12; Adafruit Matrix Portal M4 with samd51j19

Code/REPL

import board
import displayio
import framebufferio
import rgbmatrix

displayio.release_displays() # Release current display, we'll create our own

# Create RGB matrix object for a chain of four 64x32 matrices tiled into
# a single 128x64 pixel display -- two matrices across, two down, with the
# second row being flipped. width and height args are the combined size of
# all the tiled sub-matrices. tile arg is the number of rows of matrices in
# the chain (horizontal tiling is implicit from the width argument, doesn't
# need to be specified, but vertical tiling must be explicitly stated).
# The serpentine argument indicates whether alternate rows are flipped --
# cabling is easier this way, downside is colors may be slightly different
# when viewed off-angle. bit_depth and pins are same as other examples.
MATRIX = rgbmatrix.RGBMatrix(
    width=128, height=64, bit_depth=6, tile=2, serpentine=True,
    rgb_pins=[board.MTX_R1,
              board.MTX_G1,
              board.MTX_B1,
              board.MTX_R2,
              board.MTX_G2,
              board.MTX_B2],
    addr_pins=[board.MTX_ADDRA,
               board.MTX_ADDRB,
               board.MTX_ADDRC,
               board.MTX_ADDRD],
    clock_pin=board.MTX_CLK, latch_pin=board.MTX_LAT,
    output_enable_pin=board.MTX_OE)

# Associate matrix with a Display to use displayio features
DISPLAY = framebufferio.FramebufferDisplay(MATRIX, auto_refresh=False,
                                           rotation=0)

# Load BMP image, create Group and TileGrid to hold it
FILENAME = "/code/team0_logos/NYJ.bmp"

# CircuitPython 6 & 7 compatible
BITMAP = displayio.OnDiskBitmap(open(FILENAME, "rb"))
TILEGRID = displayio.TileGrid(
    BITMAP,
    pixel_shader=getattr(BITMAP, 'pixel_shader', displayio.ColorConverter()),
    tile_width=BITMAP.width,
    tile_height=BITMAP.height
)

# # CircuitPython 7+ compatible
# BITMAP = displayio.OnDiskBitmap(FILENAME)
# TILEGRID = displayio.TileGrid(
#     BITMAP,
#     pixel_shader=BITMAP.pixel_shader,
#     tile_width=BITMAP.width,
#     tile_height=BITMAP.height
# )

GROUP = displayio.Group()
GROUP.append(TILEGRID)
DISPLAY.root_group = GROUP
DISPLAY.refresh()

# Nothing interactive, just hold the image there
while True:
    pass

Behavior

Images look corrupted / weird (look at uploaded file)

Description

Only happens with some bitmap files. Maybe because the bitmaps palette index 0 is while and 255 is black?

Additional information

I was messing around with my own build of circuit python and discovered that it looks like `displayio_convert_color' treats the color as a rgb332 color because colorspace.depth is 8 right. Or would it be 24.
I have 4 displays running and the code is running as a .mpy file from a sd card

Here is the bmp I used.
NYJ.bmp.zip

Here is all the bmp files that don't work
Bitmaps.zip

And this bitmap works
wales.bmp.zip

[dhalbert]

Could you please include the .bmp in your report, not using file.io, which is only temporary? If you can't upload a .bmp, zip it up and upload it and add that as a file. See "Paste, drop, or click to add files" below the post editing box.

Also maybe include a file that is working. If you have more than one which looks wrong, include that too.

[carson-coder]

Ok I will edit the post

[dhalbert]

BTW, identify -verbose NYJ.bmp and similar gives you all kind of info about the file, including its indexed colormap. identify is from ImageMagick.

[carson-coder]

I made a python script to take a indexed bmp image and output a picture as if that bmp was rgb332 and this is what it got

so its not just thinking the image is rgb332

[carson-coder]

BTW, identify -verbose NYJ.bmp and similar gives you all kind of info about the file, including its indexed colormap. identify is from ImageMagick.

[removed by @dhalbert due to size]

[dhalbert]

I reproduced your problem on a single panel with the Matrix Portal S3 (I can't find my Matrix Portal M4 at the moment).

I saw a similarly corrupted image. However, when I read the file into GIMP and then export it as .bmp again, with no changes, it displays properly:
NYJ1.bmp.zip
Try that.
The indexed palette as described by identify -verbose is exactly the same. However, there are these differences. The Compression difference might be the significant one. The new file is just slightly larger.

[dhalbert]

I tested with 8.2.9 and 9.0.0-alpha.6: no difference. BTW, you can also use the # # CircuitPython 7+ compatible code in the example instead of the older code, but both work.

[dhalbert]

This is also helpful: https://www.metadata2go.com/. Note that the size is 946 for NYJ.bmp, and it's RLE, and NYJ1.bmp is None, and the size is 1024. It seems like there's a misinterpretation of RLE for some reason for these files. Did you make them exactly according to the recipe in the scoreboard guide?

[dhalbert]

OK, this looks like #7450, which reports the same thing. We should complain about compressed files but we're not checking carefully enough.

[carson-coder]

Thank you. Is there a way to decompress the images in python/bash. I have a lot of image that need to be decompressed.

[dhalbert]

On the command line:
convert NYJ.bmp -compress None NYJ-uncompressed.bmp

[carson-coder]

Thank you.