Back in CPSC 101, we did a lot of image editing. We only used PPM images in class and I was thinking the other day about how even though I hated the project at the time, it was pretty interesting. So, I decided to re-code some of it in Python. Basically, all I’ve done is written a script that will allow the conversion of any color PPM image into greyscale. I feel like this can be pretty handy, as it’s fast and seems to do a pretty good job.
Here’s the before image (Ironically, I had to convert to another image format before posting):
And here’s the output:
A few particulars about the files and scripts:
I used the P3 header, which is easier because it allows you just to write ASCII into the file.
Also, you must ensure that the header of the input photo must only have 3 lines. I’ve found that if you convert a JPEG from Gimp, it adds its on line in the header. It was easy to just do ‘nano in.ppm’ in terminal and remove the line they put in.
The script can be run using ‘python grey.py <input filename>’
This ONLY works on PPM images. Maybe someday I’ll look into another image format.
And that’s it!
Here’s the code, check it out: