Transform

A basic command-line image processing script for bitmap images written from scratch in C.

Support

• Supports BMP v3, BMP v4 and BMP v5.
• Supports 24-bit and 32-bit bitmap images.
• Does not support color palettes.
• Does not support compression.

Usage

./transform [options] <input file> <output file>

Options:

• -i

  Invert colors of image.

  ./transform sampleImages/marbles.bmp invert.bmp -i

  Original	Inverted

• -l <factor>

  Apply log gamma transform (natural log) with a multiplication <factor>.

  ./transform sampleImages/lightLarge.bmp log.bmp -l 30

  Original	Log Gamma

• -e <factor>

  Apply inverse log gamma transform (natural log) with a multiplication <factor>.

  ./transform sampleImages/lightLarge.bmp inverseLog.bmp -e 0.001

  Original	Inverse Log Gamma

• -p <gamma>

  Apply power-law gamma transform - RGB intensities are raised to the power (1 / <gamma>).

  ./transform sampleImages/harvard.bmp gamma.bmp -p 2.0 

  Original	Power-Law Gamma

  To apply the inverse gamma transform use (1 / original gamma) as <gamma> value.

  ./transform sampleImages/harvard.bmp inverseGamma.bmp -p 0.5

  Original	Inverse Power-Law Gamma

  Example: To get inverse of <gamma> = 2.0 set <gamma> = 0.5

  ./transform sampleImages/harvard.bmp gamma.bmp -p 2.0 
  ./transform gamma.bmp retrieve.bmp -p 0.5 

  Original	Power-Law Gamma	Inverse of Power-Law Gamma

  Note: We have significant banding or loss of data in the highlights as the original image's hightights were already blown out.

  We can also do this in a single step:

  ./transform sampleImages/lightLarge.bmp retrieveLight.bmp -p 2.0 -p 0.5

  Original	Retrieved

• -g

  Convert image to 8-bit greyscale image.

  Note: Any options provided after this will be discarded.

  ./transform sampleImages/cat.bmp grey.bmp -g

  Original	Greyscale

• -b

  Bit plane slicing:

  Convert image to greyscale and generate 8 1-bit monochrome images representing each bit plane ranging from MSB (Most Significant Bit) to LSB (Least Significant Bit) - Bit numbering.

  Note: Any options provided after this will be discarded.

  ./transform sampleImages/lightLarge.bmp out.bmp -b

  Original	Greyscale

  BitPlane 0	BitPlane 1	BitPlane 2	BitPlane 3

  BitPlane 4	BitPlane 5	BitPlane 6	BitPlane 7

• -s[=ATTR_LIST]

  Set a range of RGB intensities to specified intensity.

  Attributes: "Ra, Rb, Ri, Ga, Gb, Gi, Ba, Bb, Bi"

  Intensities a to b are set to intensity i.

  ./transform sampleImages/harvard.bmp intensities.out -s150,255,255,50,100,100,200,255,200

  Original	Intensities

Note:

The order in which the options are provided are the order in which the transforms are applied.