Color to transparency writes a new alpha channel from one rule. You give a color as # and six hex digits, and a tolerance from 0 to 64. Tolerance 0 changes only pixels with that exact RGB. A higher tolerance changes a pixel when the Euclidean distance in 8-bit RGB is less than or equal to the tolerance. Alpha is ignored while matching. A matched pixel is written as RGBA 0,0,0,0. Every other pixel keeps the RGBA the browser decoded. The download is a PNG.
Zero matches is a successful PNG with a changed count of 0. Anti-aliased edges remain unless the tolerance reaches them. The page does not flood-fill from the corners and does not guess a background. A matching pixel in the middle of a shape changes too. Do not read the title as automatic subject removal.
Read the HEX first on the Image Color Picker if you do not already know it. After the PNG is built, the Image Transparency Checker can confirm the new alpha counts. The result only stays transparent in a format that stores alpha. The JPEG vs PNG vs WebP article covers that choice. This page always writes PNG, even when the input was JPEG.
The preview uses a checker behind the canvas so the new holes are visible. The file never leaves the browser.
Black at tolerance 0 changes a pixel of 0,0,0 and leaves a pixel of 10,0,0 alone, including that pixel’s original alpha. A pixel of 10,10,10 against black is about 17.3 away, so tolerance 17 leaves it and tolerance 18 clears it. Tolerance 64 can reach a pixel 40 red-units away. An input with no pixel near the chosen color still downloads, with changed equal to 0. A partial-alpha pixel is tested on RGB only, then the match becomes fully clear.
A leading zero such as 08 is rejected, and a decimal is rejected. The field is text so the page can keep that rule. Invalid HEX clears any previous PNG instead of keeping a stale download. The changed count is the number of pixels the rule matched, including a pixel that was already 0,0,0,0 if its RGB matched.
A white page photographed under uneven light will not become a clean cutout at tolerance 0, and a large tolerance will eat into the subject. That is the rule working, not a failure of detection, because detection is not what this page does. Use a small tolerance for a flat logo color. Use the transparency checker on the download when you need the counts rather than the preview.
Tolerance 0 matches that RGB exactly. A higher tolerance uses Euclidean distance in 8-bit RGB, up to 64. Alpha is not part of the match. Matched pixels become 0,0,0,0. Other pixels stay as decoded. Zero matches is still a PNG. Anti-aliased edges stay unless the tolerance reaches them. This is not background detection. Output is PNG. JPEG, PNG, and WebP in. Limits: 8 MB, 8,000 px, 16 megapixels.
No. Every pixel within the distance of the HEX color changes, including a match in the middle of the subject. There is no subject detection.
Only that exact RGB changes. Alpha is not part of the match. A higher integer allows a larger Euclidean distance, up to 64.
No. The page still builds a PNG and reports 0 changed pixels.
The new alpha has to live in a format that stores it. JPEG input is allowed, and the result is still PNG.
