BYTETOOLS

Image Levels Adjustment

Adjust image levels online with input black and white points, midtone gamma and an output range, guided by a live histogram and one-click auto levels.

Drop an image to adjust its levelsProcessed locally — never uploaded

What is the Image Levels Adjustment?

The ByteTools levels adjuster gives you the same controls Photoshop and GIMP put in their Levels dialog: an input black point and white point that decide which tones become pure black and pure white, a midtone gamma that brightens or darkens everything in between, and an output pair that compresses the final range.

  • Input black point, white point and midtone gamma plus an output range
  • Live luminance or per-channel histogram with your points drawn on it
  • Auto levels and Auto per channel buttons using 0.5% percentiles
  • Per-channel editing to neutralise a colour cast
  • 256-entry lookup table applied at full resolution on export
  • Runs entirely in your browser — nothing is uploaded

How to use the Image Levels Adjustment

  1. 1

    Drop a photo into the upload area — the histogram appears as soon as it loads.

  2. 2

    Choose the editing channel: RGB for everything at once, or red, green or blue on its own.

  3. 3

    Drag the input black and white points to the ends of the histogram data, then set the midtone gamma.

  4. 4

    Pull the output black and white points inward if you want a faded, matte finish.

  5. 5

    Use Auto levels (0.5%) for an instant fix, then click Download PNG to save.

About the Image Levels Adjustment

The ByteTools levels adjuster gives you the same controls Photoshop and GIMP put in their Levels dialog: an input black point and white point that decide which tones become pure black and pure white, a midtone gamma that brightens or darkens everything in between, and an output pair that compresses the final range.

A live histogram sits above the sliders with your black and white points marked on it, so you can see the empty space at each end of the tonal range instead of guessing. Auto levels sets those points at the 0.5% percentiles for you, and you can edit RGB together or tune the red, green and blue channels separately to kill a colour cast.

Adjustments are compiled into a 256-entry lookup table and applied to canvas pixel data in your browser, so the work is 100% local and your photo is never uploaded anywhere. You preview at a reduced size while you drag, then export the full-resolution result as a lossless PNG.

Frequently asked questions

What do image levels actually control?

Levels remap the tonal range of a photo. The input black and white points say which source values collapse to 0 and 255, gamma bends the midtones between them, and the output points decide how much of the 0-255 range the result is allowed to use.

How do I fix a flat, washed-out photo with levels?

Drag the input black point right until it meets the left edge of the histogram data, and the input white point left until it meets the right edge. That stretches the tones you actually have across the full range, which restores contrast instantly. Auto levels does the same thing at the 0.5% percentiles.

What is the difference between levels and brightness/contrast?

Brightness and contrast shift and scale every pixel uniformly, so they clip detail easily. Levels let you set the endpoints and the midtone gamma independently, so you can brighten shadows without blowing out highlights. That is why levels is the standard tool for tonal correction.

Why does gamma 2.0 make my image brighter and not darker?

This tool follows the Photoshop and GIMP convention, where the pixel value is raised to the power of 1 divided by gamma. Gamma above 1 therefore lifts the midtones and gamma below 1 darkens them, so mid-grey 128 becomes about 181 at gamma 2.0.

Can levels remove a colour cast?

Yes. Switch the editing channel to red, green or blue and set the black and white points for each one separately, or press Auto per channel to do it automatically. Stretching each channel to its own endpoints neutralises most casts from mixed indoor lighting.

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