Calculate new width & height of image keeping ratio constant & should have desired number of pixels-CodePudding

I have to resize images in such a way that :-

1.) ratio should be constant (but small variations are acceptable)

2.) resultant image should have total number of pixels in given range

My pseudo algorithm is as follows:- (Total Pixels should be between 28000 & 30000 demonstrated in algorithm)

ratio=width/height
for i in range(width):
    for j in range(height):
        if (i!=0)|(j!=0):
            no_of_pixels=i*j
            if (no_of_pixels>=28000)*(no_of_pixels<=30000):
                new_ratio=i/j
                if abs(new_ratio-ratio)<=0.006:
                    new_width=i
                    new_height=j

My pseudo algorithm works properly but issue is that it is clearly not efficient. Is there any better way to speed it up?

CodePudding user response：

Just find the existing area and calculate how much you should reduce (or enlarge) it:

import math

area = width * height
factor = math.sqrt(30000.0 / float(area))
new_width = int(width * factor)
new_height = int(height * factor)