Sepia Image

Sepia filter recolors every pixel with one matrix and downloads a PNG of the same width and height. Pure red becomes 100, 89, 69, and there is no strength slider.

The matrix on three colors

Each pixel uses three weights. Red is 0.393, 0.349, and 0.272. Green is 0.769, 0.686, and 0.534. Blue is 0.189, 0.168, and 0.131. The results are rounded and clamped between 0 and 255. Alpha is copied unchanged. Pure red, 255, 0, 0, becomes 100, 89, 69. Pure white, 255, 255, 255, becomes 255, 255, 239. Pure black stays 0, 0, 0. A 200 by 80 picture stays 200 by 80. The button reads Download PNG and stays disabled until a preview exists. The file name ends in sepia-image.png, using the original base name, or the word image when the file has no name.

What the tone does not do

There is no amount slider, so you cannot ask for a lighter or heavier brown. Grayscale Image is a different matrix that sets the three channels equal. This page does not. A JPEG source is saved as PNG. EXIF is whatever the browser applied when it decoded the file. This page does not read a separate orientation tag after that. A drop that is not a picture shows Please upload an image. The canvas matches the decoded pixel size. Transparent pixels keep their alpha, so a logo with clear corners stays clear in those corners while the colored pixels shift.

How to check the white point

A white pixel should not stay 255, 255, 255. The blue channel lands on 239. If a photo that was mostly white looks slightly warm, that is the matrix, not a white-balance control. Black pixels stay black, so a dark edge does not lift. If you need the original colors, keep the file you dropped. The PNG is a new picture. Pressing Download PNG again uses the same preview until you drop a new file. There is no reset slider because there is no slider. Black at 0, 0, 0 is the third check, and it stays 0, 0, 0. A 200 by 80 photo stays 200 by 80. That size check is separate from the color check.

The picture stays in the tab

The pixels are rewritten in this browser. The photo is not uploaded. A large file stays large, because the pixel count does not drop. The PNG can be heavier than a JPEG source. Keep the original if you might want the color back. The preview and the download use the same canvas. Pure red is the easiest pixel to test because the green and blue inputs are zero, so each output channel is only the red weight times 255, rounded. 0.393 times 255 rounds to 100. 0.349 times 255 rounds to 89. 0.272 times 255 rounds to 69. If your red patch does not land on those three numbers, the preview is not this matrix. White is the second test, and its blue channel is 239 rather than 255.