Image Brightness & Contrast
Adjust brightness and contrast of any image in your browser with live preview. Download as PNG.
Pure browser JavaScript (HTML canvas) — no upload.
How to use this tool
- Choose an image.
- Drag the Brightness and Contrast sliders.
- Click Download.
Adjust brightness and contrast of any image in your browser with live preview. Download as PNG.
How it works
The Image Brightness and Contrast tool lets you adjust two fundamental tonal qualities of any photo: brightness shifts all pixel values lighter or darker, while contrast stretches or compresses the difference between light and dark areas. Sliders for both controls update a live preview as you drag.
Brightness adjustment adds or subtracts a fixed value from every pixel's color channels. Increasing it makes the whole image lighter; decreasing it makes everything darker. Contrast adjustment expands the tonal range -- making darks darker and lights lighter -- when increased, or compresses it when decreased, which makes everything look flat and gray.
These two adjustments are among the most commonly needed quick fixes for photos. Use brightness to correct an overexposed or underexposed shot, and contrast to give a flat, washed-out image more visual depth. Download the adjusted image as PNG when done. All processing is local; nothing is uploaded.
Worked example
Fix an underexposed photo taken in low light
- Upload the dark photo.
- Drag the brightness slider to the right until faces and details become visible.
- If the result looks flat, increase contrast slightly to restore depth.
- Check the preview and fine-tune both sliders.
- Click Download to save the corrected PNG.
A brighter, more visible photo with natural-looking tonal range.
Common mistakes to avoid
- Pushing brightness so high that highlight areas clip to pure white and lose all detail.
- Increasing contrast on an already high-contrast image, causing shadows to block up and become pure black.
- Making adjustments then accidentally uploading a new image before downloading, losing the edited version.
Key terms
- Brightness
- A uniform offset applied to all pixel values, making the whole image lighter (positive) or darker (negative).
- Contrast
- The degree of difference between the lightest and darkest tones in an image; high contrast looks punchy, low contrast looks flat.
- Clipping
- When adjusted pixel values exceed the 0-255 range and are clamped to pure black or pure white, losing detail in shadows or highlights.
Frequently asked questions
- Is my image uploaded?
- No — all pixel operations run locally via Canvas getImageData.