Written by Alex Chen · Reviewed by Jane Smith · July 26, 2026
Convert images to grayscale, sepia, duotone, or inverted colors. Custom duotone with your own colors.
Upload an image and apply an effect.
This tool applies one of four photographic effects to an image: grayscale, sepia, duotone with two custom colors, or invert. Every pixel is read from the source file, transformed by a small set of formulas, and written to an output canvas that you can download as a PNG. The processing runs entirely in your browser, so the image is never uploaded.
Each pixel stores red, green, and blue channels between 0 and 255. The grayscale mode computes the simple average of the three channels, gray = (r + g + b) / 3, rounds it, and writes the same value to all three channels. That places the pixel somewhere on the neutral ramp from black to white, preserving the overall brightness of the original pixel.
Take a pixel with rgb(120, 180, 60). The grayscale average is (120 + 180 + 60) / 3 = 120, so the output pixel is rgb(120, 120, 120). Invert flips each channel to its complement: (255 - 120, 255 - 180, 255 - 60) = (135, 75, 195). Sepia blends the channels with fixed weights, giving a warm tone of roughly rgb(197, 175, 137).
The human eye is far more sensitive to green than to red or blue, so many editors use a luminance formula that weights the channels: 0.299R + 0.587G + 0.114B. For the same pixel, luminance gives 0.299 x 120 + 0.587 x 180 + 0.114 x 60 = 148, noticeably brighter than the average of 120. This converter uses the simple average, so green-heavy images may look slightly darker here than on tools that apply luminance weighting.
Sepia applies a classic transformation matrix: red becomes 0.393r + 0.769g + 0.189b, green becomes 0.349r + 0.686g + 0.168b, and blue becomes 0.272r + 0.534g + 0.131b, each clamped at 255. Invert maps every channel to 255 minus its value, producing a color-negative look. Duotone first converts the image to grayscale, then maps each gray level as a ratio between 0 and 1 to a blend of your shadow and highlight colors: color = shadow + (highlight - shadow) x ratio.
Grayscale and duotone collapse three channels into one, discarding hue and saturation information permanently. Invert keeps the color relationship but reverses it, and sepia remaps the palette. None of the effects can be reversed from the output, so keep the original file if you might want the color version later. The output is always a PNG, which keeps the result lossless after the effect is applied.
The simple average weights red, green, and blue equally, while your eye weights green most heavily. Scenes that are mostly red or blue therefore darken more than they would under luminance conversion.
No. The original color information is gone once the effect is applied. Download the processed PNG, but keep the source file separately if you need the original.
The alpha channel is left untouched by the effects, so transparent areas of a PNG stay transparent in the output.
Duotone produces the two-tone poster look common in editorial design. Pick a dark shadow color and a light highlight color, and every gray level in between becomes a blend of the two.
Yes. The processed canvas is exported as a PNG, which preserves the effect without additional compression artifacts.
Entirely in your browser through the Canvas API. The image is read from your device and written back to it, with no upload step.
Grayscale suits printed documents where color would raise ink costs, archival scans that must not drift with color shifts, and portraits where removing color focuses attention on tone and contrast. Sepia fits vintage-styled shots, duotone matches posters and brand assets, and invert is useful for previewing negatives or artistic experiments. Avoid grayscale when the image's meaning lives in color, such as charts, maps, or medical scans.
Because the average weights every channel equally, distinct colors can collapse to the same gray. Pure red, pure green, and pure blue each carry one channel at 255 and the others at zero, so all three average to 85 and become identical mid-gray. A logo that relies on color contrast between such primaries can lose its separation completely after conversion. When the distinction between elements matters, inspect the preview before downloading.
The preview and the download come from the same processed canvas, so what you see is exactly what the PNG will contain. Apply an effect, study the result, switch modes, and compare before committing to a download. Because every mode re-reads the original image rather than the previous output, moving from sepia back to grayscale produces the same clean result as the first pass, with no accumulated damage.
These transformations only recolor existing pixels; they cannot rescue a blurry photo, correct exposure, or remove noise. Grayscale hides a color cast but keeps underexposure, and invert does nothing for an image that is already balanced. Use the tool after the source is as good as it will get, and save any further corrections, such as contrast or brightness, for an editor that offers those controls.