Adjust image levels

Levels sets the black point, white point and midtones of an image in your browser, which is the correction that fixes most flat or hazy photographs. Auto reads the histogram of the file you loaded, discards 0.1% of the pixels from each end so one stray speck cannot decide the range, and moves the black and white points to where the tones actually start and stop. You can work on RGB together or on the red, green and blue channels one at a time, which is how a colour cast gets corrected.

How it works

  1. Drop your images Drag one or more images onto the page. The histogram of the loaded image is drawn behind the sliders.
  2. Press auto, or set the points by hand Auto clips 0.1% off each end of the histogram and sets the black and white points from what survives. The black point, white point and midtones sliders move them yourself, from 0 to 255.
  3. Switch channel if there is a colour cast RGB moves all three channels at once. Choosing R, G or B moves only that channel, which is what corrects a cast rather than the overall contrast.
  4. Compare against the original Turn on show the original to swap the preview back to the untouched pixels. The export is unaffected by it.
  5. Apply and download Choose a format — keep, PNG, WebP or JPEG — then apply. One file downloads on its own, several arrive as a ZIP.

Questions

Do my photos get uploaded when I adjust levels?
No. The image is decoded, corrected and re-encoded inside your own browser tab, and no file or pixel is sent anywhere. file4edit has no server for images and no account, and the tool keeps working after the first load with the network switched off.
What exactly does the auto button do?
Auto reads the histogram of the loaded image, discards 0.1% of the pixels from each end, and sets the black and white points to where the remaining tones begin and end. The clip matters: a single dust speck or hot pixel at level 0 would otherwise make the raw minimum say 0 when the picture really starts at 40.
What are the limits of this levels tool?
It works at 8 bits per channel — every setting collapses into 256-entry lookup tables, one per channel, so a deeper source is corrected at 8-bit precision. Alpha is never touched, and one set of settings goes to every file in the batch, so photographs shot under different light need a pass each.

Every tool