Why the Thumb Impression Is Square When Nothing Else Is
240×240 is a perfect 1:1 square — unlike the photo (tall portrait), signature (wide), or declaration (very wide) formats used elsewhere in the same application. This matters because a thumb impression, unlike a full-page document, is naturally close to square already — a stamp-pad impression is roughly as wide as it is tall. Even so, an uncropped photo of the whole sheet of paper (which is not square) will still distort when forced into an exact 240×240 output unless you frame and crop it correctly first.
If you photograph the entire A4 sheet with lots of blank space around the impression, resizing to a square 240×240 either squeezes the image or centers a small impression inside a mostly-empty square — either way, the actual ridge detail ends up smaller in the frame than it should be.
How to Frame the Impression for a Clean Square Crop
Photograph the impression from directly above, keeping the camera parallel to the paper — a tilted angle distorts a square shape into a trapezoid, which becomes obvious once forced into an exact square. Frame the shot so the impression sits roughly centered with a small margin of white space on all sides, rather than capturing the whole sheet of paper from a distance.
If your phone or scanning app supports it, crop to a square (roughly equal width and height) around the impression before uploading here, rather than relying on this tool alone to compensate for a rectangular, uncropped source photo.
What Happens If the Source Isn't Square
Uploading a non-square photo still works — this tool resizes it to 240×240 regardless — but the result is rarely as legible as a properly cropped one. A tall or wide source photo gets squeezed into the square frame, which can visibly distort the ridge pattern rather than just shrinking it proportionally. Crop close to square before uploading for the cleanest result.
Preparing the Impression Itself
Use a black stamp pad on plain white paper, press the left thumb firmly, lift straight up without dragging, and let it dry before photographing. A clear, well-inked impression on a properly squared crop compresses more predictably to the 20-50KB target than a rectangular, poorly cropped source.
Before You Submit
After resizing to 240×240, zoom into the preview and confirm the impression looks proportionally correct — not stretched wider or taller than it should be, and not shrunk into a small mark surrounded by excess white space. If it looks distorted, crop the source photo closer to square and resize again.
FAQ
240x240 is a 1:1 square ratio. If your source photo captures the whole rectangular sheet of paper rather than a tightly cropped, roughly-square area around the impression, forcing it into a square output can distort the ridge pattern.
Use the left thumb only. Banking application portals normally ask for left thumb impression. Uploading the right thumb can cause rejection unless the official notification gives a special alternative instruction.
Use black stamp pad ink on plain white paper. A small stationery-shop inkpad is enough. Do not rub pen ink directly on the thumb because it spreads unevenly and often smudges.
Use a fresher inkpad or apply slightly more pressure on the pad. Press the left thumb firmly on paper and retake the photo in better light.
Yes. Use the rear camera, bright light, direct top-down angle and a steady hand. Keep the paper flat and avoid shadows on the impression.
Before, if possible. Crop the source photo to roughly a square around just the impression using your phone's gallery crop tool or the Image Crop tool, then upload here for the exact 240x240 resize.
Yes, if it has clean black ink and gives a sharp print. Old or dry pads create faint ridges, so test once on rough paper before the final attempt.
Use plain white unlined paper only. Lines, printed marks and colored paper can confuse verification and make the final image look unprofessional.
Yes. Always retake a smudged impression. Compression cannot restore ridge detail when the source print is dragged or blurred.
Go back to the source photo and crop it closer to a square before resizing again — a mismatched source aspect ratio is the most common cause of a squeezed or distorted result.
Yes. The common minimum is 20KB. A file below that may be rejected by the portal or may become too compressed for visual checking.
It is simply the clean white background around the impression. Keep it free from stray ink marks so the thumb pattern stands out clearly.
They are not recommended. Press the thumb directly on the stamp pad because it gives natural and even ink distribution across the ridges.
Use one clear final impression. If the first attempt is poor, use a fresh area or fresh paper instead of placing multiple impressions together.
Retake the impression with better ink, white paper, good light and direct camera angle. Then process it again to 240x240 pixels and 20KB to 50KB.