Brighter or darker · −100 to +100 · Up to 5 images
Image Brightness Adjuster
Shift the brightness.
Keep your framing.
Lighten or darken a whole image with one value from −100 to +100, compare the live preview and save JPG, PNG or WebP at the original size. It is a flat RGB shift, so it cannot bring back detail in areas that are already pure white or pure black.
Add images to adjust
Drop, paste or choose up to 5 images.
JPG · PNG · WebP · BMP · GIF · SVG · HEIC · 10 MB each
Checking available output formats…
Set each image, or type a value (−100 to +100) and press Apply to all.
Live brightness preview
Brightness & download
0 keeps the original brightness. Positive values lighten and negative values darken; each colour channel stops at 0 or 255.
Settings guide
Move the tones. Watch for clipping.
One number changes the picture. Format and quality only decide how the result is stored.
| Control | What it does | Good starting point | Concrete example |
|---|---|---|---|
| Brightness slider | Adds the value to the red, green and blue level of each pixel, or subtracts it. | Try +10 to +25 | New images start at 0, which leaves them unchanged. |
| Exact value | Type the same setting as a whole number. | −100 to +100 | Decimals such as 12.5 are refused until corrected. |
| Apply to all / Reset all to 0 | Gives every loaded image the number in the batch box, or 0. | Matching set | Apply to all replaces earlier values; it does not add +20 on top of +20. |
| Output format and quality | Images added as JPG are saved as JPG unless you switch; quality affects only JPG and WebP. | PNG for transparency | Need a smaller file? Adjust here, then use the Image Compressor. |
| Adjust all / Download ZIP | Saves each image in turn, then packs the ready files together. | ZIP for 2+ files | An image edited after saving is left out of the ZIP until you adjust it again. |
The exact pixel rule
Add equally. Stop at 0 and 255.
Saved value = the original value + your setting, kept between 0 and 255
Worked out for red, green and blue separately. Transparency is not changed.
| Original RGB | Setting | Saved RGB |
|---|---|---|
| 80, 120, 200 | +30 | 110, 150, 230 |
| 80, 120, 200 | −30 | 50, 90, 170 |
| 220, 240, 250 | +30 | 250, 255, 255 · two channels hit the top |
| 10, 20, 30 | −30 | 0, 0, 0 · the three shades merge into black |
Simple arithmetic for opaque pixels, checked against this tool's output. Once two different shades hit 255 or 0 they become identical, and setting the value back on the saved copy cannot separate them again.
Not exposure or gamma
A camera exposure change scales light; this tool adds a fixed number. Dark and light areas move by the same amount, so shadows look flatter than with a curves edit.
Brightness is not contrast
Contrast pushes light and dark apart; brightness moves them together. For a dull, washed-out look, try the Image Contrast Adjuster as well.
Always from the original
Every change starts from the image you added. Moving from +20 to +30 gives +30, not +50, so you can try values freely.
Colours can look different
Adding the same number to every channel makes strong colours look paler when brightened and muddier when darkened. Small values keep this effect mild.
Before & after
A brighter image. Not recovered exposure.
These illustrations show the general effect. They are separate from your live result, and any labels in them belong to the screenshots.
Processing notes
Pixel arithmetic. On your device.
The tool reads the pixel values in your browser, changes them in small strips and saves a new file.
What happens to your images
When to use it
A whole-image shift. A deliberate small change.
| Use | Suggested setting | What to check |
|---|---|---|
| A dim indoor phone photo for WhatsApp or Instagram | +15 to +30 · JPG | Faces and white walls should keep their texture rather than turning flat white. |
| A product photo that looks a little too dark | +10 to +20 · JPG or WebP | Compare the label text and the background; a pure-white background stays white. |
| A graphic or banner that feels too bright | −10 to −25 · PNG | Areas that were already pure white become flat light gray, not new detail. |
| Several photos from one shoot | One value · Apply to all | Check each result; the tool does not measure or match their exposure for you. |
| A faded scan or a photo that looks dull | Try contrast first | Brightness alone often makes faded images look flatter; use the Image Contrast Adjuster. |
Output choices
Change the pixels. Then pick the file.
| Output | Transparency | Quality setting | Consideration |
|---|---|---|---|
| PNG | Kept | Not used | No compression artifacts; a photo saved as PNG is usually much larger. |
| JPG | Filled with white after the change | 0.10–1.00 | The usual choice for photos; very low quality adds visible blocks. |
| WebP | Kept | 0.10–1.00 | Offered only after this browser passes a WebP save test. |
Troubleshooting
Read the tones. Then the settings.
Highlights turned flat white
Bright areas reached 255 and lost their differences.
- Move the slider back toward 0.
- Watch the sky, skin and white clothing.
- Try the contrast tool for a dull photo.
Shadows became solid black
Dark values fell below 0 and were stopped there.
- Use a smaller negative value.
- Check hair, clothing and dark corners.
- Start again from your original photo.
The background turned white
JPG cannot store transparency, so it is filled white.
- Choose PNG or WebP instead.
- The checkerboard is only a preview aid.
- Press Adjust image again after switching.
The download button disappeared
Changing brightness, format or quality removes the old file.
- Press Adjust image or Adjust all.
- The ZIP button shows how many are ready.
- Errors are listed in the notice line.
Brightness questions
Before you save the adjusted image
How do I make an image brighter or darker?
Add an image, then move the Brightness slider or type a whole number from −100 to +100. Positive numbers lighten and negative numbers darken; 0 leaves the picture as it was. Press Adjust image, check the result and download it.
What does a brightness value of +30 mean?
Thirty is added to the red, green and blue value of every pixel, and anything above 255 stops at 255. For example, RGB 80, 120, 200 becomes 110, 150, 230. It is a fixed step on the 0–255 scale, not a percentage or an exposure stop.
Can it fix an overexposed or underexposed photo?
Only partly. It can make the whole picture look lighter or darker, but detail that the camera recorded as pure white or pure black is not in the file, so no setting can bring it back. Large values can also flatten texture and change how saturated colours look.
What is the difference between brightness and contrast?
Brightness moves every tone up or down by the same amount. Contrast moves light and dark tones apart or closer together. A dull, grey-looking photo usually needs contrast; a photo that is evenly too dark or too light needs brightness.
Does setting 0 bring back my original photo?
While the image is still loaded here, 0 shows it exactly as added; your original file is never changed. A saved -brighter or -darker copy cannot be undone if some tones were clipped, so keep the original. Reset this image returns to 0 with the default format and quality.
Can I use one brightness value for several photos?
Yes. Add up to five images, type a value in the batch box and press Apply to all; Reset all to 0 removes the change from every image. Names and formats are kept, and each image can still be set on its own afterwards. Adjust all saves them one by one.
How are the adjusted files named and zipped?
Names end in -brighter, -darker or -original depending on the setting. Download ZIP packs every ready file without saving it again; if only some are ready, the button shows how many. Repeated names get a number, and single downloads still work.
Which file types can I add, and how large?
You can add JPG/JPEG, PNG, WebP, BMP, GIF, HEIC/HEIF and self-contained SVG images: up to five at once and 10 MB each. An image may have up to 20 MP and 16,384 px on a side, all images together up to 40 MP, and a saved file may reach 96 MB.
Will the size and transparency stay the same?
Yes for size: the saved image has the same width and height, with nothing cropped or resized. Transparency is not adjusted and stays in PNG and WebP files. JPG cannot store it, so transparent areas become white after the brightness change.
Why does the preview look a little different from the download?
The preview is reduced to fit within 900 px and is shown before compression. The saved file has every original pixel, and JPG or WebP compression adds its own small changes. Open the downloaded file at full size to judge fine detail.
Does the quality setting change the brightness?
No. Quality only controls how strongly JPG and WebP files are compressed, and PNG does not use it. Lower quality usually means a smaller file with more visible artifacts. Changing brightness, format or quality removes the earlier file, so press Adjust again.
Are my photos sent anywhere?
No. Brightness changes and ZIP files are made in your browser, and your photos are not sent to our server. Only a HEIC photo that this browser cannot open itself downloads a free decoder from jsDelivr; your image is not part of that request. Animated GIFs keep their first frame and SVGs become pixels.
What does Stop do, and is my work kept after a refresh?
Stop cancels the image being processed and skips the rest; finished files stay ready. Images, settings and ready files are not saved, so a refresh or closing the tab clears them. Download your results before leaving the page.
Ready to adjust your image brightness?
Return to your settings, or browse the image tools and the full tools directory.