The short answer
Why use Threshold?
Color fixes are easier to judge one change at a time. The live preview shows blown highlights, muddy shadows, or a color cast before you save.
Threshold makes every pixel pure black or pure white. It averages the red, green, and blue values and compares the result with the Threshold level: 50 splits at middle gray, lower values turn more of the image white, and higher values turn more of it black.
It suits signatures, stamps, and line drawings photographed on paper. Uneven light is the usual problem: one corner of the page turns black while faint lines vanish in the opposite corner. Shoot the page in even daylight, or crop to the signature first so the level only has to suit a small area.
The average is a plain one, not weighted for how bright each color looks to the eye, so colored ink can land on the other side of the line than you expect. Move the level a few points either way. Transparent areas stay transparent. For a few gray steps instead of two, use Posterize.
Where Threshold fits
Signatures
Turn a phone photo of your signature into crisp black on white for a document.
Rubber stamps
Clean up a photographed stamp or seal for a letterhead or form.
Line art
Prepare a pencil sketch for tracing, vinyl cutting, or laser engraving.
Start to finish
How to use Threshold
- 01Tap Choose image and pick the photo of the signature, stamp, or drawing.
- 02Move Threshold level from 50. Raise it until thin strokes are solid black; lower it if specks of paper turn black.
- 03Tap Apply changes, then Download result to save the black-and-white PNG.
What to expect from Threshold
| Check | What it means here |
|---|---|
| Supported input | JPEG, PNG, WebP, GIF, BMP, SVG and browser-supported AVIF images |
| Main controls | Threshold level, one slider from 0 to 100 |
| Output | A PNG image with the adjustment applied |
| Working limit | 50 MB and 50 megapixels per image |
Threshold tips
- Crop to the signature before you apply, so one level suits the whole area.
- Shoot the page in even daylight; a shadow across one corner turns solid black.
- Blue or red ink is judged by a plain average of R, G and B, so test a few points either side of 50.
- Transparent areas stay transparent, so a cut-out logo keeps its clear background.
Threshold FAQ
Something missing? Ask us.
What Threshold level should I use for a signature?
Does Threshold upload my file?
Is Threshold free to use?
Why did Threshold fail or look wrong?
Related tools
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