IMAGE PROCESSING REFERENCE

8-Bit RGB Brightness Value Calculator

This reference models a simple additive brightness operation for 8-bit RGB channels. It adds the adjustment to each channel and clamps the result to the valid 0–255 range.

Formula

output = clamp(input + adjustment, 0, 255). This is a useful reference model, but individual image editors can use different brightness curves.

Brightness adjustment table

Input	-128	-64	0	64	128	255
0	0	0	0	64	128	255
32	0	0	32	96	160	255
64	0	0	64	128	192	255
96	0	32	96	160	224	255
128	0	64	128	192	255	255
160	32	96	160	224	255	255
192	64	128	192	255	255	255
224	96	160	224	255	255	255
255	127	191	255	255	255	255

Why clamping matters

An 8-bit channel cannot store values below 0 or above 255. A simple additive adjustment therefore clips extreme dark and bright values at those limits.

This table is a mathematical reference, not a specification of the FileTools brightness algorithm. Use an actual output sample when documenting implementation-specific behaviour.

Input	-128	-64	0	64	128	255
0	0	0	0	64	128	255
32	0	0	32	96	160	255
64	0	0	64	128	192	255
96	0	32	96	160	224	255
128	0	64	128	192	255	255
160	32	96	160	224	255	255
192	64	128	192	255	255	255
224	96	160	224	255	255	255
255	127	191	255	255	255	255

Input	-128	-64	0	64	128	255
0	0	0	0	64	128	255
32	0	0	32	96	160	255
64	0	0	64	128	192	255
96	0	32	96	160	224	255
128	0	64	128	192	255	255
160	32	96	160	224	255	255
192	64	128	192	255	255	255
224	96	160	224	255	255	255
255	127	191	255	255	255	255

Input	-128	-64	0	64	128	255
0	0	0	0	64	128	255
32	0	0	32	96	160	255
64	0	0	64	128	192	255
96	0	32	96	160	224	255
128	0	64	128	192	255	255
160	32	96	160	224	255	255
192	64	128	192	255	255	255
224	96	160	224	255	255	255
255	127	191	255	255	255	255