What formula is used for the grayscale conversion?

The ITU-R BT.601 luminance formula: 0.299 x Red + 0.587 x Green + 0.114 x Blue. This weights channels by human visual sensitivity, producing a perceptually accurate result rather than a simple average.

Is transparency preserved?

Yes. The alpha channel is not modified. Transparent areas in the original PNG remain transparent in the grayscale output.

Is the output truly grayscale or just desaturated?

The output uses the luminance formula, not CSS desaturation. Each pixel's R, G, and B channels are all set to the same luminance value, producing a true grayscale image.

Is my image uploaded to a server?

No. The pixel manipulation runs entirely in your browser using the Canvas API.

Grayscale Image Converter

Convert any color image to grayscale using the ITU-R luminance formula — side-by-side preview, instant download.

How to use this tool

1Click the upload zone and select any image file.
2The grayscale version is generated instantly and shown alongside the original.
3Click 'Download Grayscale' to save the PNG.

About Grayscale Image Converter

Converting a color image to grayscale isn't as simple as removing saturation — a naive approach produces flat, low-contrast results. This converter uses the ITU-R BT.601 luminance formula: gray = 0.299 x R + 0.587 x G + 0.114 x B. The green channel is weighted most heavily because the human eye is most sensitive to green light; red is weighted second; blue least. This produces a perceptually accurate grayscale that matches how humans perceive brightness. The conversion reads every pixel's RGB values via getImageData(), applies the formula, and writes the result back with putImageData(). A side-by-side preview shows the original and grayscale versions before you download. Transparency (alpha channel) is preserved in the output PNG. Photographers preparing images for print, designers creating monochrome assets, and developers generating grayscale thumbnails are the typical users.

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