BMP EDITING

This repo focuses on editing BMP images at pixel level using C. For ease of use I used QDBMP library. And for Grayscale techniques I followed Tanner Helland's article.

Original Image

Negative

To get negative of an image, we just invert each color in each pixel of the image.

Greyscale

While converting a colored image to greyscale, a grey value is calculated from RGB values of the pixel and all the 3 RGB values are updated to the same grey value. This grey value depends upon the algorithm used.

Average Method

In this method grey value is simply the average of all 3 RGB values of a pixel.

Correcting for the human eye (Luma Method)

This method uses an algorithm specified by the original ITU-R recommendation (BT.709, specifically) to calculate the grey value.

Desaturation

This method takes the average of the max and min values of a pixel and assigns it as the grey value.

Decomposition

There are two ways to decompose an image.

Max Decomposition

This uses the max value of all the 3 channels for the grey value.

Min Decomposition

This uses the min value of all the 3 channels for the grey value.

Single Color Channel

This method uses data from a single color channel.

SCC Red

This uses the red channel directly as gray.

SCC Green

This uses the green channel directly as gray.

SCC Blue

This uses the blue channel directly as gray.

For better understanding of the SCC method, I am including another example here.

Original Image

SCC Red

SCC Green

SCC Blue

Custom shades of grey

In this method, the greyscale image is generated based on the number of shades of grey we define. As the number of shades of grey increases the image gets better and better.

2 shades of grey 3 shades of grey 4 shades of grey 8 shades of grey 16 shades of grey 32 shades of grey 64 shades of grey 128 shades of grey 256 shades of grey