Understanding bmp image files

[pranny]

Hello,
I want to read a BMP file, do some processing and then write it in a
new file. The problem is in the third step. For reading the file, i
have converted the file into decimal numbers, representing the pixel
values. Then i perform calculations on those decimal numbers. Now i am
unable to convert those into the format as required by the "bmp" file.
Any one, who is into image reading/manipulation, please help.

[dazzler]

using putpixel with Image module could be one solution?

here's one example which reads image and converts all red values which are over 50 to 255 =)

import Image
 
pic = Image.open("test_bmp.bmp")
 
x_size, y_size = pic.size
 
for i in range(0,x_size):
   for j in range(0,y_size):
      pixel = pic.getpixel((i,j)) #get color value in tuplet (R,G,B)
      if pixel[0] > 50:  #if red component have bigger value than 50 change it to 255
         pic.putpixel((i,j),(255,pixel[1],pixel[2]))
 
pic.save("new_image.bmp","BMP")
 

more reading
http://www.pythonware.com/library/pi...book/image.htm

[pranny]

Thanks, initially i was planning not to use PIL and do it with my own stuff. but as the size of my project grew, i am using PIL :-)

[raubana]

I have never used just regular modules to edit and save .bmp files, but I do know that you can use pygame to fix this problem! All you have to do is convert your file data into a Surface (if your data is an array, srfarray can convert it, too), then say

pygame.image.save(SurfaceName, "NameOfFile.bmp")

It's pretty simple. I've even used this trick to make pictures look mixed up!