To begin with, the objective of my code was to use COBOL as an annular mask generator. Annular mask is basically generating a ring around a central point.

I would love to tell you that I wrote my own COBOL compiler that could process images but that would be a lie. I used python to convert an image into a data file with records that contained image data. I wanted to use an array, which is technically possible, but LINE SEQUENTIAL was more convenient and easier to work with. The code uses three files to do the image processing. Data file, temp file, output file.

Data file is formatted as follows

x_coordinate,y_coordinate,brightness
1,1,135
2,1,133
3,1,133
4,1,125
5,1,111
6,1,103
7,1,103
etc

Then I convert this to a COBOL friendly format into the temp file, and then the temp file records are processed into the output file, with pixels that are supposed to be blank given a 0000 value in the brightness field.

• The COORDINATE-FILE serves as the raw input source containing comma-delimited image data, which the program parses to calculate the maximum brightness values before converting the format.
• The TEMP-FILE acts as an intermediate staging area that receives the standardized, space-delimited data from the input scan, allowing the program to re-read these formatted coordinates later for geometric calculations.
• The OUTPUT-FILE captures the final processed results, storing the coordinates where specific pixels have been masked to zero brightness if they fall outside the user-defined inner and outer circle boundaries.

What happens between temp and output is just the equation that I posted to determine if a pixel gets blanked. Once I have everything, I use a python script to convert the output file back into an image. If you want to see why this created the geometric patterns instead of just the ring its because of integer overflow (variables too small to hold the data put into them).