Convert strange raw image

[sfreak]

Hi!

I have some files here that are 800x600, 1 byte per pixel. Each byte has the following bits: (MSB) 0000000RGB (LSB) , 1 bit per color makes 8 colors. Can I 'convert' this to a sane image format using ImageMagick?

Thanks,
Sebastian

[anthony]

the 'stream' command does have formating output to handle this type of weird image. But I am not certain of the syntax.
Check on the main IM website.

[sfreak]

Hi,

I had a look at the stream command. It appears to only be good in the image -> raw data direction. I need to go the other way though, from strange raw data to some standard image format.

I guess I will have to write a little program myself...

Sebastian

[el_supremo]

I've been playing with this problem for a while this morning because I thought that using a colour lookup table should work.
I wrote a program to create a test binary file (bits.rgb) and reading that raw data back in is easy:

Code: Select all

convert -size 800x600 -depth 8 gray:bits.rgb bits_raw.png

Converting this to rgb wasn't so easy, mainly because I couldn't come up with a way to create the required colour lookup table with IM, so I wrote a program to create one (bits_clut.png which is here: http://members.shaw.ca/digipete/bits_clut.png )
Note that the clut must have 256 colours. I tried to make one that had just 8 colours but the -clut operation seems to interpolate between colours whether you like it or not if the clut is less than 256 colours. So the clut that I generated has the first 8 colours set to the required RGB values and the rest are black.

Then converting to an rgb image is also easy:

Code: Select all

convert bits_raw.png bits_clut.png -interpolate Integer -clut bits_new.png

The Integer -interpolate tells IM not to interpolate the colours.

Putting the two together in one command:

Code: Select all

convert -size 800x600 -depth 8 gray:bits.rgb bits_clut.png -interpolate Integer -clut bits_new.png

Pete

[sfreak]

Hey Pete,

thank you! That is exactly what I was looking for! I had no idea the -clut option even existed since I used a slightly outdated ImageMagick version. After updating your commands work like a charm.

I guess there is nothing that can't be done with ImageMagick after all!

Cheers,
Sebastian

[el_supremo]

FWIW:
I figured out how to generate the clut image with IM's -fx operator:

Code: Select all

convert -size 1x256 ( xc:black -fx "j&4" ) ( xc:black -fx "j&2" ) ( xc:black -fx "j&1" ) -combine bits_clut.png

Pete