Contact Sheet Maker

What a contact sheet is

A contact sheet is an index of photographs arranged as small proofs on one or more pages. Film photographers traditionally exposed strips of negatives against photographic paper. A digital contact sheet serves the same practical purpose: it lets an editor, client or photographer compare a sequence, refer to filenames and mark selections without opening each full-resolution file.

The page geometry is physical. A4 measures 210 × 297 mm in the ISO 216 paper series. US Letter measures 8.5 × 11 inches (215.9 × 279.4 mm), a size covered by the ANSI preferred paper-size standard. The selected margin is removed from all four edges; gaps separate neighbouring cells; the remaining width is divided by the chosen number of columns. Rows are then fitted into the remaining page height and additional photographs continue on numbered pages.

A practical proofing example

Suppose a portrait A4 sheet uses 12 mm margins, a 6 mm gap and four columns. The usable width is 210 − (2 × 12) = 186 mm. Three gaps consume 18 mm, leaving 168 mm for photographs, so each cell is 42 mm wide. The maker calculates how many matching rows fit vertically, reserves space for captions when enabled and starts another page when the grid is full.

Printing and colour caveats

The PDF has the exact selected physical page size. Print it at Actual size or 100%. JPEG pages are rendered with the pixel dimensions of a 300-pixels-per-inch page, but the browser canvas toBlob() specification records 96 dpi when the format supports resolution metadata; use the PDF when physical print size must be unambiguous. Decoding uses the browser’s createImageBitmap() image-orientation handling, then re-encodes the pixels. This removes embedded metadata such as the Exif GPS fields documented by the Library of Congress and flattens transparency on white. Output is browser-managed RGB, not a colour-managed ICC, CMYK or PDF/X prepress file.