Histogram Equalization

Apply the histogram equalization algorithm to redistribute the brightness distribution of the image's pixels, stretching contrast in the luminance domain so that detail in both shadows and highlights becomes more visible. Adjustable strength, processed entirely locally in your browser.

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Drop a photo or click to upload

PNG, JPG, WEBP, BMP

What Is the Histogram Equalization Tool?

Histogram equalization is a classic image enhancement algorithm. It redistributes pixel brightness to make the histogram more uniform, boosting overall contrast.

It is ideal for backlit, underexposed, or hazy photos, bringing hidden detail to light.

How to Equalize a Histogram

Follow these steps:

  • Drop or upload the photo you want to enhance.
  • Adjust the strength as needed (100% by default).
  • Click Equalize to see the result.
  • Download the enhanced image as a PNG file.

Tips

  • Works best on low-contrast, hazy photos.
  • A strength around 50% gives a more natural look.
  • Noise may become more visible after processing — pair with Image Denoise if needed.

Frequently Asked Questions

What is histogram equalization?+
Histogram equalization remaps pixel brightness so the image's brightness histogram is more evenly distributed. It spreads brightness concentrated in a narrow range across the full range, significantly boosting contrast.
How is it different from auto contrast?+
Auto contrast only does a linear stretch, while equalization performs a non-linear mapping based on the cumulative distribution function. It uses the full brightness range more thoroughly and is especially good at enhancing detail in low-contrast images.
Will it introduce color casts?+
The tool equalizes the luminance (grayscale) channel while keeping each pixel's color proportions unchanged, so it will not introduce color casts.
Is my photo uploaded anywhere?+
No. All processing happens locally in your browser — your photos never leave your device.

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Histogram Equalization — free online histogram equalization, histogram equalize, contrast enhancement, image enhancement, equalize image, histogram equalizer. No signup required. Works in your browser.