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100kb

署名圧縮

署名や指紋の画像を、厳しい容量制限（20KB以下など）に合わせて最適化します。背景のコントラスト調整も可能です。

Exam Guidelines Compliance

Compress and Clean Signature and Thumb Images under 20KB

Signature and left thumb impression uploads on exam portals usually have strict requirements, requiring files to be between 10KB and 20KB. Furthermore, shadow-heavy phone camera scans can result in low-contrast signatures which get rejected. Our tool lets you resize dimensions, increase contrast to create a clean white background, and compress files client-side to ensure compliance under 20KB.

How to Use 署名圧縮

Follow these simple steps to optimize and prepare your files client-side:

1

Upload Signature Scan

Select the photo of your signature or thumb impression (captured on plain white paper).

2

Adjust Scale & Contrast

Clean up background shadows and scale to standard dimensions (e.g., 350x350 pixels or 140x60 pixels).

3

Download Signature JPG

Preview the file size to verify it is under 20KB, then download the optimized signature.

Frequently Asked Questions

Common questions regarding file security, dimensions, and portal regulations:

Does this tool support left thumb impressions?
Yes. Left thumb impressions follow the same size guidelines (usually under 20KB) and clean background requirements as signatures. You can crop, clean, and compress them here.
What color ink should I use for signatures?
Most portals prefer black or blue ink on plain white paper. Avoid ruled paper or background shadows, as automated screening systems might reject them.
Will my signature lose its original lines?
No, the image compression algorithms preserve line outlines while shrinking the solid background data to keep the file size minimal.

Suggested Next Steps / Related Tools

写真サイズ変更

証明写真をパスポートやビザの申請用に、ローカルで指定のKB数（50KB以下など）に一瞬でリサイズします。

写真・署名結合

証明写真と署名画像を縦または横に結合し、容量を100KB以下に収めた1つの画像ファイルを生成します。

背景切り抜き

証明写真の背景を自動で切り抜き、標準の白または青色の背景に完全にオフラインで置き換えます。