Perceptual weighting
Channels contribute according to perceived brightness instead of a flat average.
Free Tool
Grayscale & Filter Converter
Convert any image to grayscale (true luminance-based), sepia tone, or inverted colors. Side-by-side preview lets you compare before and after. Output is always lossless PNG so there's no quality loss from the conversion.
Grayscale · Sepia · InvertBefore/after previewLossless PNG outputNo media uploadFree to use
Watch the workflow
Convert to grayscale, sepia tone, or inverted — lossless PNG output, browser-only
How it works
- Drop any colour image — PNG, JPG, WebP, or AVIF
- Select the effect: Grayscale (luminance-weighted), Sepia (warm brown tone), or Invert (negative)
- Download the result as a lossless PNG — all colours are converted, transparency is preserved
Frequently asked questions
What is luminance-weighted grayscale?
Human eyes are more sensitive to green than red or blue. Luminance weighting (0.299R + 0.587G + 0.114B) produces a natural-looking black and white rather than a flat average of the three channels.
Does the grayscale conversion work on transparent PNGs?
Yes. The tool converts only the RGB channels — the alpha channel is preserved unchanged. A transparent PNG remains transparent after conversion.
What is the difference between Sepia and a warm photo filter?
Sepia applies a fixed warm-tinted desaturation that mimics aged photographic prints. The Image Filter tool offers more nuanced LUT-based film grade presets for modern colour work.
Related tools
Tone transformation
Choose the monochrome treatment, not merely “remove colour”
Luminance-weighted grayscale, sepia, and invert reveal different structure and mood while keeping a live before-and-after reference.
RGB → Y
Luminance conversion
Three distinct states
Neutral grayscale, warm sepia, and colour inversion solve different visual tasks.
Original comparison
Switch treatments without accumulating transforms on the previous result.
Know before you process: Grayscale conversion cannot recover tonal detail from clipped black or white regions.
Ready to try it?
Free, private, no signup. Lossless PNG output.
Convert to grayscale →