Toolstia

Toolstia / Grayscale image converter

Convert an image to grayscale

Drop in a photo and turn it into black and white. You can also try sepia, inverted colours or a harsh black-and-white scan look, and fine-tune brightness and contrast. Everything runs in your browser.

Drop an image here, or click to choose

JPG, PNG or WebP. Nothing is uploaded.

How it works

  1. Drop in your photo.
  2. Choose an effect and adjust brightness and contrast.
  3. Download the result.

How grayscale is made

Each pixel is turned into a grey level using the standard weights for how the eye sees colour (about 30% red, 59% green and 11% blue). This looks more natural than simply averaging the colours.

Pure black and white

This effect makes every pixel either black or white, depending on a threshold you set. It is useful for signatures, line drawings and documents that will be printed on a basic printer.

Sepia and invert

Sepia gives a warm brown, vintage tone. Invert swaps every colour for its opposite, which can help make light text on a dark scan readable.

Saved at full size

The preview on the page is smaller to stay fast, but the download is processed at the full size of your original picture.

Questions

Is my photo uploaded?

No. It never leaves your device.

Does it work with PNG transparency?

Yes, transparent areas stay transparent when you save as PNG or WebP.

Will it reduce quality?

PNG keeps full quality. JPG and WebP apply their usual compression.

Can I undo?

Choose "No effect" and set brightness and contrast to 0, or choose another image.

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