What does Adjust Brightness do?
Adjust Brightness is a free online tool that can increase or decrease image brightness. The PNG result from Adjust Brightness is a separate copy to inspect before you use it elsewhere. One possible use is dark previews adjusted for screen reading.
Brightness and contrast adjustment changes an image's tonal look with two numeric settings. The brightness field ranges from -100 to 100, and contrast has its own range with a default of zero.
This is useful for testing a brighter or flatter rendering before a picture is placed in a file. Start with small changes: strong adjustments can clip highlights, crush shadow detail or make a subtle gradient appear abrupt.
Brightness changes the light level of the picture. Contrast changes the gap between dark and light areas.
Those controls can work against each other if pushed too far. Check a bright highlight and a dark shadow in the same test. A clipped white area cannot regain detail from a brighter setting.
Change picture brightness and contrast online: steps
Before using Adjust Brightness, decide what the new copy must contain and where it will be used. Set brightness and contrast based on the source, keeping a reference copy to judge changes. Review the upload area and all values required by the current Adjust Brightness form.
Choose the source
Look for lost detail in the brightest part of a photo. For Adjust Brightness, choose one source from your device. Keep a source copy for another attempt.
Review the form values
Brightness (-100 to 100) controls a value used by Adjust Brightness. The starting Brightness (-100 to 100) value is 20.
Contrast (-100 to 100) controls a value used by Adjust Brightness. The starting Contrast (-100 to 100) value is 0.
Run the file task
Use Process Adjust Brightness after checking the source and form values. Wait for the job to finish. An error means this attempt failed.
Save and check the output
Check the lightest and darkest regions, faces and any text that needs to stay readable. Store the output on your device. Name this copy separately from the original.
Change tones: uses for Adjust Brightness
Adjust Brightness can help with low-contrast scans tested for legibility. It can also be used for owned pictures prepared for a file layout. The PNG result from Adjust Brightness must suit the intended reading or editing step, so keep the source until that check is complete.
- Dark previews adjusted for screen reading.
- Low-contrast scans tested for legibility.
- Owned pictures prepared for a file layout.
- Brightness alternatives compared before final editing.
Formats and limits for Adjust Brightness
The Adjust Brightness form accepts the image formats in the table sources. Each Adjust Brightness upload can be up to 300 MB, which equals 300 MiB. The allowed suffixes on the Adjust Brightness page do not prove that a source has valid content inside it.
| Accepted formats | Maximum file size | Output |
|---|---|---|
| JPG, JPEG, PNG, WEBP, TIFF | 300 MB per file (300 MiB upload limit) | PNG |
A brightened image cannot recover information already clipped in the original. Tonal edits do not establish color accuracy or replace calibrated photo work.
How this tool works
Adjust Brightness uses ImageMagick to handle the source on the server. The Adjust Brightness request uses your chosen input rather than any local editing project left on your device. Check the PNG contents produced by Adjust Brightness before treating them as ready for another app or reader.
For Adjust Brightness, your browser uploads the source to our file-processing server. This is a server task, not local editing.
Files are due for deletion within 1 hour. Cleanup runs during normal service operation. Keep a local download for future use.
Adjust Brightness questions and answers
If Adjust Brightness gives an unexpected result, start by checking the source type and the values used in the form. Check the PNG contents from Adjust Brightness as well as the filename or displayed message. For another result type, compare Adjust Brightness with the separate tools described in these answers.
What matters when using Adjust Brightness?
Read a scan's text against its newly adjusted background. View that area at its intended display size. Note any differences that affect your purpose.
Why try Auto Enhance?
Auto Enhance offers another task beside Adjust Brightness: automatically adjust image levels, gamma and tonal range. Auto Enhance returns PNG. The stated PNG output from Adjust Brightness matches a listed input type for Auto Enhance.
Why try Grayscale Image?
Grayscale Image offers another task beside Adjust Brightness: convert image to black and white grayscale. Grayscale Image returns PNG. The stated PNG output from Adjust Brightness matches a listed input type for Grayscale Image.
Why try Sharpen Image?
Sharpen Image offers another task beside Adjust Brightness: enhance image sharpness and clarity. Sharpen Image returns PNG. The stated PNG output from Adjust Brightness matches a listed input type for Sharpen Image.
What if my PNG result does not open?
For a failed Adjust Brightness result, first confirm that the download completed and that the viewer supports PNG. Try another local viewer for that format.
Record any error message for support. Keep private source material out of the report.
How do I report a problem with Adjust Brightness?
Contact support with the Adjust Brightness page name, source format and the error you saw. Mention any relevant form settings you chose. Do not send passwords or private attachments.