Question

I am attempting to read a bitmap manually. So I read the bitmap file using a filestream. There wasn’t a problem until I had to deal with 24 bit bitmap files. Is there a method to actually read a 24 bitmap image into a 24 bit array ?

I hold a 8 bit bitmap image in a byte array like this

byte[] fileBufferArray = new byte[fileLength];  

Answer 1

A few options:

1. If you’re not too worried about memory (you don’t have a large number or very large bitmaps open), you can store it as 32-bit numbers instead. Often the fourth byte is then interpreted as “alpha” (a blending specifier when rendering the image on a background.) Most modern image manipulation libraries treat color images in this way now.

2. You can pack the colors into a byte array and access them individually. RGB and BGR are the two most common packing orders. Usually you also end up putting padding bytes at the end of each row so that the width in bytes lines up with DWORD (4-byte) boundaries.

3. You can split the image into three separate byte array ‘planes’, which are basically 8-bit images for Red, Green and Blue respectively. This is another common format when doing image processing, as often your filtering steps operate on channels independently.