Image Threshold Tool
Convert a local image to black and white using one adjustable brightness threshold. Processing takes place locally in your browser.
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One brightness threshold for the whole image
For each decoded pixel, brightness is (299R + 587G + 114B) / 1000. Brightness at or above the threshold becomes RGB(255,255,255); lower brightness becomes RGB(0,0,0). At threshold 128, gray RGB(128,128,128) is white and RGB(127,127,127) is black. Raising the threshold increases the set of black pixels. This is a weighted RGB brightness rule, not adaptive thresholding or OCR.
Transparency and output
The decoded alpha channel is retained. Transparent areas remain transparent, so the visible background is not necessarily white. The output keeps the decoded image dimensions and uses PNG; there is no format, region, batch or zoom selector. Animation and source metadata are not preserved. Fine details can disappear, and color gradients are reduced to two RGB levels; keep the original and compare the downloaded file.
Input limits
The file must have an image type and be decodable by the browser. The per-file budget is 25 MiB (26,214,400 bytes) and 24,000,000 decoded pixels. These are rejection limits, not a guarantee of smooth processing on every device. Image processing takes place in the browser, and the source file is not overwritten.
Processing takes place locally in your browser.