jangko / nimBMP

BMP encoder and decoder

nimBMP

BMP Encoder and Decoder written in Nim

supported standard color mode:

• 1 bit
• 4 bit uncompressed and compressed
• 8 bit uncompressed and compressed
• 16 bit with color mask
• 24 bit
• 32 bit with color mask

both inverted(top-down) and non inverted mode supported

Supported color conversions:

• 32/24bit to 1, 4, 8, 24 bit
• automatic palette generation

Basic Usage

import nimBMP

let bmp24 = loadBMP24("image24.bmp") #load bmp as RGB 24 bit
let bmp32 = loadBMP32("image32.bmp") #load bmp as RGBX 32 bit

# the default container is string,
# if you want the output container is seq[uint8],
# you can specify it as second param
let bmp24seq = loadBMP24("image24.bmp", seq[uint8]) #load bmp as RGB 24 bit into seq[uint8]
let bmp32seq = loadBMP32("image32.bmp", seq[uint8]) #load bmp as RGBX 32 bit into seq[uint8]

the returned object from loadBMP24 or loadBMP32 have fields:

• bmp.width -> the width of the decoded image
• bmp.height -> the height of the decoded image
• bmp.data -> contigous pixels stored in Nim string
  • loadBMP24 will produce r1,g1,b1,r2,g2,b2,...,rn,gn,bn
  • loadBMP32 will produce r1,g1,b1,x1,...,rn,gn,bn,xn

Create BMP from raw pixels

import nimBMP

saveBMP32("image32.bmp", rgbx_pixels, width, height)
saveBMP24("image24.bmp", rgb_pixels, width, height)
saveBMP8("image8.bmp", gray_pixels, width, height)

The second param to saveBMPxx is raw input pixel. The input pixels can be a sequence of bytes in string container or seq[uint8] container

The internal algorithm of saveBMP will choose the best target format after it analyze the image's content.

Installation via nimble

nimble install nimBMP