Image filters
Black and white, invert, sepia, brightness and contrast, applied live. The photo never leaves your computer.
No image yet.
Black and white, done properly
There is a right way and a lazy way to remove colour, and the difference is visible. The lazy way averages the red, green and blue channels. The right way weights them, because the eye is nothing like equally sensitive to the three.
Green carries roughly 71% of perceived brightness, red about 21%, blue only 7%. Average them instead and a vivid red and a vivid blue collapse to the same middling grey, skies come out far too pale, and the picture loses the tonal separation that makes a black and white photograph work. This uses the standard broadcast weights, which is what photo software does.
Brightness and contrast are not the same dial
Brightness shifts every pixel the same amount. It rescues an underexposed picture and flattens one that was already fine, because it moves the highlights along with everything else.
Contrast pivots around mid grey: raising it pushes the shadows down and the highlights up, so the picture gains separation without changing overall exposure. On a flat, hazy photograph contrast is almost always the one you actually want.
Nothing accumulates
Every adjustment is computed from the original image each time, not applied on top of the last one. Move a slider back to zero and you have precisely what you started with.
That matters because the usual alternative degrades: applying contrast to an image that has already had contrast applied quantises the tones twice and leaves banding in smooth areas like skies. Here you can push a slider back and forth as often as you like and the result depends only on where it ends up.
Where the quality actually goes
The arithmetic is lossless. Saving is not, if you save as JPG, which throws away a little detail every time it writes a file. Adjusting and saving once is invisible. Adjusting, saving, reopening and adjusting again, repeatedly, is how a photograph ends up looking soft.
If you are going to come back to it, save as PNG in between and make the JPG once at the end. To make the file smaller rather than different, the resize tool does far more than a filter can.
Common questions
- Is my photo uploaded?
- No. It is read from your own disk, adjusted in your browser, and handed straight back. Nothing is sent to us or to anyone else, and nothing is stored.
- Why does your black and white look different from other tools?
- Because the three colour channels are weighted rather than averaged. The eye is far more sensitive to green than to blue, so a flat average turns a vivid red and a vivid blue into the same muddy grey and makes skies far too pale. This uses the standard broadcast weights, which is what photo software does and why the result has proper tonal separation.
- Will this reduce the quality?
- The adjustment itself is arithmetic on the pixels and loses nothing. Saving does: JPG is lossy, so each save costs a little. Save as PNG if you plan to keep adjusting the same file, and as JPG when you are finished.
- Can I undo?
- Everything works from the original, every time. Move a slider back to zero or press None and you have exactly the image you started with, because nothing is ever applied on top of a previous adjustment.
- Does black and white make the file smaller?
- A little, usually. A greyscale JPG compresses somewhat better than a colour one because the colour channels carry almost no information, but the saving is modest, typically 10 to 20%. If size is the goal, the resize tool will do far more.