Comparing two QColor objects, finding most similiar

[morph]

Hi.

I'm converting a QImage bitmap file between formats using PyQt.
After conversion I want to get back to the starting colours, because they change a tiny bit after converting.

Is there any accurate way to compare QColor objects and find the most similar one?

I've tried to compare rgb values, but it's not accurate enough:

def nearest_color(self, color):
 
        col = QColor(color)
        r = col.red()
        g = col.green()
        b = col.blue()
        ranks = {}
        for orig_color in self.originalImageColors:
            orig_rgb = QColor(orig_color)
            diff = abs(orig_rgb.red() - r) + abs(orig_rgb.green() - g) + abs(orig_rgb.blue() - b)
            ranks[diff] = orig_color

def nearest_color(self, color):

        col = QColor(color)
        r = col.red()
        g = col.green()
        b = col.blue()
        ranks = {}
        for orig_color in self.originalImageColors:
            orig_rgb = QColor(orig_color)
            diff = abs(orig_rgb.red() - r) + abs(orig_rgb.green() - g) + abs(orig_rgb.blue() - b)
            ranks[diff] = orig_color

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Test data:
Original colours: 4281742902L, 4278190335L, 4278190144L, 4294967295L
Colours after conversion: 4281742902L, 4278190335L, 4278190144L, 4294967295L
I need to map matching colors

[Caolan O'Domhnaill]

Python has bitwise operators I would suggest turning it into a bitstream and do a bit by bit comparison.

https://wiki.python.org/moin/BitwiseOperators

Hi.

I'm converting a QImage bitmap file between formats using PyQt.
After conversion I want to get back to the starting colours, because they change a tiny bit after converting.

Is there any accurate way to compare QColor objects and find the most similar one?

I've tried to compare rgb values, but it's not accurate enough:

def nearest_color(self, color):
 
        col = QColor(color)
        r = col.red()
        g = col.green()
        b = col.blue()
        ranks = {}
        for orig_color in self.originalImageColors:
            orig_rgb = QColor(orig_color)
            diff = abs(orig_rgb.red() - r) + abs(orig_rgb.green() - g) + abs(orig_rgb.blue() - b)
            ranks[diff] = orig_color

def nearest_color(self, color):

        col = QColor(color)
        r = col.red()
        g = col.green()
        b = col.blue()
        ranks = {}
        for orig_color in self.originalImageColors:
            orig_rgb = QColor(orig_color)
            diff = abs(orig_rgb.red() - r) + abs(orig_rgb.green() - g) + abs(orig_rgb.blue() - b)
            ranks[diff] = orig_color

To copy to clipboard, switch view to plain text mode 

Test data:
Original colours: 4281742902L, 4278190335L, 4278190144L, 4294967295L
Colours after conversion: 4281742902L, 4278190335L, 4278190144L, 4294967295L
I need to map matching colors