Image Brightness & Contrast
Image Brightness & Contrast adjusts the brightness and the contrast of a PNG, JPEG, or WebP image, in your browser, with a live preview.
Drop an image here (PNG, JPEG, WebP — max 20 MB)
How to use it
- Upload a PNG, JPEG, or WebP image
- Move the Brightness slider (-100 to +100)
- Move the Contrast slider (-100 to +100) and check the preview
- Click Apply adjustments and download the result
The brightness slider runs from -100 to +100 and adds a fixed offset to every red, green and blue channel — negative values darken toward black, positive values lighten toward white, and 0 leaves the image unchanged. The contrast slider also runs from -100 to +100 and scales each channel around mid-gray (128): positive values push darks darker and lights lighter, negative values pull everything toward the middle, and 0 is neutral. Brightness is applied first, then contrast, and the preview and the export use exactly the same math, so what you see is what you get. The effect is computed pixel by pixel; the preview works on a canvas of at most 700 pixels and is never recomputed at full resolution while you drag a slider, and the full-resolution pass only runs when you click Apply adjustments, with a Processing indicator. The alpha channel is never read or changed, so transparent areas keep their transparency, and the output has the same dimensions and format as the source. This is a numeric adjustment of the decoded RGB channels: it does not recover highlight or shadow detail that is already clipped to pure white or black, and it is not a professional exposure or color-correction workflow. JPEG and WebP are re-encoded, so EXIF, XMP or ICC metadata may be changed or dropped, and very large images are limited to about 24 megapixels for this per-pixel adjustment. Unlike Image Grayscale / Sepia (which changes the overall tone), Image Blur / Pixelate (which obscures pixels) or Image Border (which adds a border), this tool only changes how bright the pixels are and how far apart the light and dark values sit. Nothing you load is uploaded or stored anywhere.
FAQ
Move the Brightness slider. Positive values add light to every pixel and shift the image toward white; negative values subtract light and shift it toward black. The preview updates as you drag; click Apply adjustments to render and download a copy.
Contrast changes how far apart the light and dark values are. Positive contrast makes dark areas darker and bright areas brighter, increasing separation; negative contrast pulls all values toward mid-gray, making the image flatter. A value of 0 leaves it unchanged.
No. If an area is already pure white or pure black in the file, that detail is gone and a simple brightness or contrast change cannot bring it back. These sliders only rescale the values that are still present.
No. The output canvas uses the exact width and height of the decoded image, so the result is the same size as the original. The tool only changes color values; it does not resize, crop or re-frame.
Yes. The alpha channel of each pixel is never read or modified, so transparent and semi-transparent areas of a PNG or WebP keep their exact transparency after the adjustment.