Signature Resizer & KB Optimizer
Trim, clean and resize a signature scan to the exact size a form requires.
A signature photographed on a phone is mostly white paper with a small mark in the middle. Portals want a tight crop at specific pixel dimensions and often between 10 and 20 KB. This tool trims the surrounding white space, boosts contrast and hits the size — on your device, with no upload.
Nothing is uploaded. Your image is read by your own browser and processed on a canvas element on your device. It never reaches a server, ours or anyone else's, and closing the tab discards it entirely.
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Result
Fill in the fields above and your result will appear here.
What the Signature Resizer & KB Optimizer does
Signature requirements are usually tighter than photograph requirements. A common specification is 140 × 60 pixels between 10 and 20 KB, which is a very small file — and a photograph of a whole sheet of paper scaled to that size leaves the signature barely visible.
The trimming step finds the actual extent of the ink by scanning for pixels darker than a threshold, crops to that region with a small margin, and scales it to fill the target. The result is a signature that fills the frame rather than floating in white space.
How to use this tool
- Sign on plain white paper with a black or dark blue pen — a thicker pen scans better than a fine one.
- Photograph or scan it in even light, keeping the paper flat and the camera parallel to it.
- Drop the image here and choose the specification your form requires.
- Leave the trim option ticked so surrounding white space is removed and contrast is improved.
- Process, check that the signature fills the frame in the preview, then download.
How trimming and sizing work
TRIM
Scan every pixel and compute luminance:
L = 0.299 R + 0.587 G + 0.114 B
Pixels below L = 200 are treated as ink.
The bounding box of all ink pixels, plus a 3% margin,
becomes the crop region.
SCALE
The cropped region is scaled to fit the target dimensions
without distortion, centred on a white background.
ENCODE
JPEG quality is binary-searched to land just under
the KB limit.
Worked example
Example: a phone photo of a signature
| Original | 3,024 × 4,032 px, 2.2 MB — signature occupies about 8% of the frame |
| After trimming | Cropped to the ink, filling the frame |
| Target | 140 × 60 px, 10–20 KB |
| Result | 140 × 60 px, about 15 KB |
Without trimming, the same photo scaled to 140 × 60 would show a signature a few pixels tall — technically the right size, and certain to be rejected.
What your result means
The signature should fill most of the frame in the preview. If it looks small, the trim did not detect the ink — usually because the photo is too dark overall or the paper is shadowed.
A file at the top of the allowed band is the right outcome. Signatures are simple images and compress well, so hitting the minimum is sometimes the harder constraint.
If trimming crops too aggressively, there is a mark or shadow being read as ink. Photograph again on cleaner paper in more even light.
Important considerations
- Sign with a black or dark blue pen. Light blue and gel pens scan poorly and may not be detected as ink.
- Photograph in even daylight rather than under a single lamp, which casts a shadow that trimming may read as ink.
- Some examinations additionally require a handwritten declaration image with its own size specification. Process it separately.
- The signature you upload should match the one you will sign on the answer sheet and admit card — mismatches are a common cause of problems at the examination centre.
- Do not sign in capital letters where the instructions require a normal signature; several notifications state this explicitly.
- Keep the original scan. If a portal rejects the upload you will need to try different dimensions.
Limitations of this tool
- Trimming uses a fixed luminance threshold. A very light signature or a heavily shadowed photograph may not be detected correctly.
- It cannot remove a coloured or patterned background — plain white paper is required.
- Output is JPEG. Forms requiring PNG are not supported.
Frequently asked questions
What size should a signature be for an exam form?
140 × 60 pixels between 10 and 20 KB is the most common Indian specification, used by IBPS among others. NTA portals often use 280 × 80. Always check the notification for your examination.
Why does my signature look tiny after resizing?
Because the original photo is mostly white paper. The trim option crops to the ink so the signature fills the frame — make sure it is ticked and that the photograph is evenly lit.
What pen should I use?
Black or dark blue, and preferably a slightly thicker nib. Light colours and very fine lines scan poorly and can be lost entirely at small pixel sizes.
Is my signature uploaded anywhere?
No. It is processed entirely in your browser and never transmitted. Given that a signature is sensitive, this matters — and it is why the tool works this way.