What does histogram normalisation do?

It stretches the range of intensity values in an image so that the darkest pixels become black and the brightest pixels become white, effectively increasing the overall contrast.

Should I use Auto Contrast?

Yes, Auto Contrast is recommended for most images as it automatically calculates the optimal 1% and 99% percentiles to improve clarity without clipping important details.

How do the percentile sliders affect my image?

The lower percentile ignores a percentage of the darkest pixels to preserve shadow detail, while the upper percentile ignores a percentage of the brightest pixels to protect highlight detail.

Which output format should I choose?

PNG is recommended for maximum quality, while JPEG or WebP are better if you need to balance file size with visual fidelity.

Is there a file size limit?

Yes, the tool supports files up to 20MB.

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Image Normalise

Normalise image histogram to enhance contrast by stretching the intensity range (British spelling)

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6 options

FilesUpload source files for this workflow.1

Image FilefileRequired

Single file max size: 20 MBSupported types: image/jpeg, image/png, image/webp, image/gif, image/bmp, image/tiff

Upload any image file (JPEG, PNG, WebP, GIF, BMP, TIFF) to enhance contrast through histogram normalisation

SettingsAdjust formats, ranges, numbers, and modes.4

Lower PercentilerangeOptional

0.110

Percentage of darkest pixels to ignore (0.1% - 10%). Lower values preserve more shadow detailUpper PercentilerangeOptional

9099.9

Percentage of brightest pixels to ignore (90% - 99.9%). Higher values preserve more highlight detailOutput FormatselectOptionalChoose output format or keep original. PNG recommended for maximum qualityQuality (1-100)numberOptionalOutput quality for lossy formats (JPEG, WebP). Higher = better quality but larger file size

TogglesEnable or disable optional behavior.1

Auto ContrastcheckboxOptionalEnabled when checkedAutomatically enhance contrast using 1% and 99% percentiles (recommended for most images)

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Image Normalise

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Examples

1. Enhancing Faded Scanned Documents

2. Optimizing Product Photos

FAQ

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