Convert Image to Grayscale

The three methods give genuinely different photographs

Converting to black and white means turning three numbers — red, green and blue — into one. There is more than one way to do that, and the choice changes the picture more than people expect. Most tools pick one silently.

Luminance is the default and the right answer most of the time. It weights the channels roughly 30% red, 59% green, 11% blue, because that is how sensitive human vision actually is — we see far more detail in green light than in blue. The result looks like a proper black and white photograph: a red jumper and a blue sky come out at believable brightness relative to each other.

Average simply adds the three channels and divides by three. It treats blue as mattering exactly as much as green, which your eye does not, so the result looks flatter and slightly muddy — reds come out too pale, blues too dark. It is the wrong choice for a photograph and occasionally the right one for a deliberately washed-out, low-contrast look.

Desaturate takes the midpoint between the brightest and darkest channel in each pixel. This is what the desaturate command in image editors does. It produces a softer, lower-contrast result that keeps midtones closer together — good for a gentle, muted feel, and good for portraits where luminance can render skin harshly.

Practical advice: start with Luminance. If the photo looks harsh or the skin tones seem wrong, try Desaturate. Reach for Average when you actively want the image to look flat.

Add contrast back — most black and white photos need it

This is the setting that most improves results and the one people skip.

Colour does a lot of work separating objects in a photograph. A green door against a brown wall is obvious in colour; in black and white both might land on the same shade of grey and the door disappears. Removing colour removes that separation, which is why so many black and white conversions look flat and lifeless.

The fix is contrast. Somewhere between +15 and +30 restores the separation for most photos, and it is the difference between a picture that looks drained and one that looks deliberate. Push further for a dramatic, high-contrast look, but watch the preview — beyond about +60 you start losing detail in the shadows and blowing out the highlights permanently.

Negative contrast flattens the image further, which is useful when the photo is going behind text and needs to recede.

The strength slider does something most tools cannot

Intensity is not an on/off switch. At 100% you get full black and white; at anything less, the result is blended back into the original colours.

That gives you partial desaturation, which is a distinct look rather than a halfway house. At around 30 to 50% you get a muted, faded photograph that still carries a hint of its colour — the sort of thing that works well as a website hero image behind a headline, as a background that must not compete with the text on top of it, or as a way to calm a photo that is too loud without going fully monochrome.

Almost every other black and white converter gives you one result and no dial. This is the setting worth playing with.

Judge it in the preview, not in your head

A before-and-after pair appears as soon as you convert, at a size big enough to compare properly. Use it. The difference between the three methods is obvious side by side and nearly impossible to predict from a description, and contrast in particular needs to be seen rather than calculated.

Everything happens on your own device, which is worth knowing given how many of the photos people convert are family pictures, portraits and personal work. No upload, no account, no watermark.

What it does not do

The output is always a JPEG, even if you put a PNG in. For a photograph that is the right format anyway, but if you specifically need PNG, convert the result afterwards.

Transparent areas of a PNG come out white, because JPEG has no transparency to keep. And there is no sepia or colour tint here — this converts to grey, it does not tone. If you want a warm vintage cast, that is a separate step.

Related tools

Convert Image Format changes the format afterwards if you need PNG or WebP rather than JPEG. Compress Image reduces the finished file for uploading, and Crop Image is worth doing first, since composition matters more in black and white than in colour.