pnmindex

Create thumbnail contact sheets from images

TLDR

Create image index

$ pnmindex [image1.pnm] [image2.pnm] [image3.pnm] > [index.pnm]

Specify size

$ pnmindex -size [100] [*.pnm] > [index.pnm]

With a title

$ pnmindex -title ["My Gallery"] [*.pnm] > [index.pnm]

Multiple columns

$ pnmindex -across [4] [*.pnm] > [index.pnm]

DESCRIPTION

pnmindex creates a visual index (contact sheet) from multiple PNM images. Each image is scaled to a thumbnail and arranged in a grid.Useful for creating image previews and galleries.

PARAMETERS

-size n

Maximum thumbnail size in pixels. Each image is scaled to fit within an N x N box while preserving aspect ratio. Default: 100.

-across n

Number of thumbnails per row. Default: 6.

-colors n

Maximum number of colors in the output image. Default: 256.

-title title

Add a title string at the top of the image.

-black

Use black background with white labels instead of the default white background with black labels.

-noquant

Disable color quantization. By default, colors are reduced for PPM input.

-quant

Enable color quantization (default for PPM input).

-quiet

Suppress informational messages.

$ # Create index of all PPM files
pnmindex *.ppm > index.ppm

# Thumbnails 150 pixels, 5 across
pnmindex -size 150 -across 5 photos/*.ppm > gallery.ppm

# With title on black background
pnmindex -title "Photos" -black images/*.pnm > contact.ppm

# Convert to JPEG
pnmindex *.pnm | pnmtojpeg > index.jpg