SSC Photo & Signature Resizer (2025/2026 Official Portal Specifications)

Mathematical Derivation & Variable Explanations: Document transformation operates on exact physical-to-pixel conversions, bi-cubic resampling, and iterative binary search compression.

• Physical Millimeter to Pixel Coordinate Mapping Equation: At standard resolution $R$ (DPI):
  $$W_{\text{px}} = \left\lceil \frac{W_{\text{cm}}}{2.54} \times R \right\rceil, \quad H_{\text{px}} = \left\lceil \frac{H_{\text{cm}}}{2.54} \times R \right\rceil$$
  For official SSC candidate photographs ($3.5 \text{ cm} \times 4.5 \text{ cm}$ at $100 \text{ DPI}$), the target is $138 \times 177 \text{ pixels}$ (or $413 \times 531 \text{ px}$ at $300 \text{ DPI}$). For official candidate signatures ($4.0 \text{ cm} \times 2.0 \text{ cm}$ at $100 \text{ DPI}$), the target is $157 \times 79 \text{ pixels}$.
• Statutory File Weight Boundaries:
  • Passport Photograph: Strictly bounded in $[20 \text{ KB}, \ 50 \text{ KB}]$ ($20,480 \le B \le 51,200 \text{ bytes}$).

  • Specimen Signature: Strictly bounded in $[10 \text{ KB}, \ 20 \text{ KB}]$ ($10,240 \le B \le 20,480 \text{ bytes}$).
• Iterative Binary Search Quality Convergence: To land precisely within the statutory file-weight envelope without trial-and-error, our algorithm executes logarithmic binary search over JPEG quality $Q \in [0.10, \ 0.98]$:
  $$Q_{k+1} = \begin{cases} \frac{Q_k + Q_{\min}}{2} & \text{if } \text{Size}(Q_k) > \text{Target}_{\max} \\ \frac{Q_k + Q_{\max}}{2} & \text{if } \text{Size}(Q_k) < \text{Target}_{\min} \end{cases}$$
  converging to optimum visual sharpness within at most $\lceil \log_2(100) \rceil = 7$ iterations.
• Lanczos-3 Resampling & Color Quantization: When downscaling large camera megapixels, standard nearest-neighbor or bilinear interpolation produces aliasing artifacts. Our pipeline uses a Lanczos-3 windowed sinc filter:
  $$L(x) = \begin{cases} \frac{\sin(\pi x)}{\pi x} \cdot \frac{\sin(\pi x / 3)}{\pi x / 3} & \text{if } |x| < 3 \\ 0 & \text{if } |x| \ge 3 \end{cases}$$
  preserving sharp facial features and pupil reflections. For stubbornly oversized images, 24-bit TrueColor buffers undergo adaptive octree color quantization, stripping imperceptible palette variations to guarantee the file stays under 50 KB without blur.
• State Public Service Commission Variations: Beyond central SSC, state boards (e.g. BSSC Bihar, UPSSSC Uttar Pradesh, MPSC Maharashtra) require 200 DPI scans with exact candidate signatures in blue or black ballpoint ink on unruled white paper.
• EXIF Metadata Stripping & Neutral Background Enforcement: Digital smartphone cameras embed heavy EXIF tags, GPS coordinates, and color profiles that inflate raw file sizes by up to 1.5 MB. Our in-browser Canvas pipeline rasterizes raw RGB pixel buffers, stripping 100% of EXIF metadata and verifying light grey or pure white background contrast.