Online Image Brightness Adjustment Tool
Increase or decrease overall image brightness. Processing takes place locally in your browser.
Start using
What Online Image Brightness Adjustment Tool actually does
Adjustment strength field defaults to 25 with bounds -100 to 100. Positive adds brightness and negative reduces it; zero is unchanged.
Checkable example
Adds 255*amount/100 to every RGB channel, then clamps to 0..255. Example RGB(100,160,240) at 20 becomes (151,211,255); at -20 becomes (49,109,189).
Controls, output and limits
The blue channel clips in the positive example: increasing brightness cannot restore lost highlight detail. This fixed offset differs from proportional darkening and white-blend lightening. It is not an exposure-stop control.
Browser-local single-image preview and download. Keep the original, compare highlight and shadow detail, and inspect the downloaded copy. No selective area mask, automatic correction or batch controls on this page.
Click Generate image and inspect the preview, then click Download to save PNG. Generate recalculates from the loaded source every time; set strength to 0 and generate to recover its decoded RGB. It does not automatically download or accumulate effects.
Adjustment strength must be a finite number between -100 and 100.
Processing takes place locally in your browser.