Online Batch Image Brighten Tool
Batch process multiple images: increase brightness by percentage. Processing takes place locally in your browser.
Start using
What Online Batch Image Brighten Tool actually does
The batch page accepts up to 30 browser-decodable image files by multiple selection or drag and drop. Each image is limited to 25 MB and 24,000,000 decoded pixels; all selected files together are limited to 100 MB and 40,000,000 decoded pixels.
Checkable example
For each RGB channel the implementation calculates channel + (255 - channel) * strength / 100, then the canvas clamps the result to a byte. At 25%, RGB(40, 100, 200) becomes approximately RGB(94, 139, 214). Positive values move colors toward white; zero preserves the channel values.
Controls, output and limits
The only effect control is Adjustment strength (%) with a displayed range from -100 to 100 and a default of 25. Press Generate image after loading files or changing the value; loading alone does not render the effect automatically.
Negative values are accepted by the control and move channel values away from white before byte clamping, so this page should not describe the negative side as a perceptually uniform darkening control. Alpha is preserved.
The result panel contains one preview per input. Download all starts individual PNG downloads named with -lighten.png; there is no ZIP, output-format selector, metadata preservation or animation preservation. Processing stays in the browser, subject to browser memory and multiple-download behavior.
Every Generate recalculates from the currently uploaded source, rather than adding another adjustment to the previous preview. Set the value to 0 and generate to restore the decoded source RGB.
Per image: ≤25 MiB and ≤24,000,000 pixels. Per batch: ≤100 MiB and ≤40,000,000 pixels. Selecting over 30 files or any invalid image rejects the whole batch.
The numeric field accepts finite fractions from −100 to 100. Empty, nonfinite or out-of-range input rejects generation and disables the old download; values are not clamped.
Processing takes place locally in your browser.