How Image Grayscale Converter Works
Grayscale mode reads every pixel's red, green and blue values and replaces them with a single luminance value (using the standard 0.299R + 0.587G + 0.114B weighting, which matches how the human eye perceives brightness) so the image keeps its full range of tones. Black & white mode goes further, turning every pixel fully black or fully white based on whether it's above or below your chosen threshold.
How to Use This Tool
- Choose or drag in an image.
- Leave Pure black & white unchecked for a standard grayscale photo, or check it and adjust the threshold for a stark two-tone result.
- Select Convert, then Download to save it.
Example
A pixel with RGB (200, 120, 60) converts to a grayscale value of about 137 — a medium-gray tone — using the luminance formula, rather than a plain average of the three numbers (which would give a slightly higher 127).
Helpful Tips
- The luminance formula weights green the most because human eyes are most sensitive to green light — a plain RGB average would look noticeably less natural.
- For scanned text or line art, black & white threshold mode often gives cleaner, more legible results than grayscale.
Frequently Asked Questions
Is my image uploaded anywhere?
No, the conversion happens entirely in your browser by reading and rewriting the image's pixel data.
What's the difference between grayscale and black & white here?
Grayscale keeps a full range of gray tones based on brightness; black & white (threshold mode) converts every pixel to either pure black or pure white with no in-between shades.
Can I undo the conversion?
Choose Another Image resets the tool, or simply re-upload the original file if you want to start over with a different setting.
This tool runs entirely in your browser. Your input is not uploaded to any server.