HTRDR-IMAGE(5) File Formats Manual HTRDR-IMAGE(5)

htrdr‑image — two dimensional image format

htrdr‑image is an image format where data is stored as plain text. Text after the # character is considered a comment and is therefore ignored, as are empty lines. The first valid line stores 2 unsigned integers representing the image definition, i.e. the number of pixels per row and column. Next, each line stores the 8 components of a pixel.

Pixels are sorted line by line, with the origin defined in the top left corner of the image. With an image definition of N by M pixels, with N the number of pixels per line and M the total number of lines in the image, the first N pixels correspond to the pixels on the top line of the image, the next N pixels are the pixels on the second line and so on.

htpp(1) can be used to convert images in htrdr‑image format into a regular PPM image. Note that the nature and unit of the data stored in a htrdr‑image file are not determined by the file format itself. Please refer to the program that generates the image for a full description of the data it contains.

The file format is as follows:

⟨htrdr-image⟩ ::= ⟨definition⟩
⟨pixel⟩
...
 
⟨definition⟩ ::= ⟨width⟩ ⟨height⟩
⟨width⟩ ::= integer
⟨height⟩ ::= integer
⟨pixel⟩ ::= ⟨cpt⟩ ⟨cpt⟩ ⟨cpt⟩ ⟨cpt⟩ ⟨cpt⟩ ⟨cpt⟩ ⟨cpt⟩ ⟨cpt⟩
⟨cpt⟩ ::= real # Pixel component

Image of 800 by 600 pixels. The comment after each pixel is the pixel's index in the image: the first and second integers are respectively the pixel's row and column index in the image:

800 600 # Image definition

# Pixels of the 1st line
2.55e-4 2.90e-5 3.75e-4 4.48e-5 3.20e-4 3.16e-5 306.484 259.7 # (1,1)
2.95e-4 3.37e-5 3.39e-4 4.16e-5 3.38e-4 4.60e-5 18.3633 2.663 # (2,1)
3.76e-4 5.43e-5 3.13e-4 3.48e-5 3.38e-4 3.32e-5 19.6252 2.670 # (3,1)
  ...
7.13e-4 1.14e-4 7.66e-4 1.35e-4 7.97e-4 1.26e-4 119.820 93.78 # (799,1)
6.59e-4 1.14e-4 7.47e-4 1.41e-4 4.39e-4 7.33e-5 24.8655 2.463 # (800,1)

# Pixels of the 2nd line
3.33e-4 6.02e-5 4.21e-4 7.66e-5 3.44e-4 3.81e-5 19.4580 2.506 # (1,2)
3.50e-4 4.93e-5 3.23e-4 2.52e-5 3.03e-4 2.42e-5 102.566 81.29 # (2,2)
2.72e-4 4.69e-5 3.41e-4 4.12e-5 2.52e-4 2.06e-5 25.5801 5.377 # (3,2)
  ...
7.52e-4 1.31e-4 8.91e-4 1.84e-4 5.48e-4 1.30e-4 46.5418 12.47 # (799,2)
6.82e-4 1.42e-4 6.61e-4 7.85e-5 4.44e-4 5.99e-5 59.8728 32.14 # (800,2)

  ...

# Pixels of the 600th line
2.69e-4 7.44e-5 2.31e-4 2.56e-5 1.95e-4 2.30e-5 43.8242 15.00 # (1,600)
4.32e-4 1.25e-4 2.22e-4 2.22e-5 2.04e-4 2.60e-5 25.5498 1.739 # (2,600)
2.78e-4 5.81e-5 2.75e-4 4.99e-5 2.17e-4 3.30e-5 38.4448 7.161 # (3,600)
  ...
3.54e-4 4.32e-5 3.07e-4 3.80e-5 2.38e-4 2.49e-5 102.893 36.98 # (799,600)
3.07e-4 2.61e-5 4.60e-4 1.13e-4 2.69e-4 4.29e-5 42.75070 11.9 # (800,600)

htpp(1), htrdr(1)

The htrdr‑image format was first developed for the htrdr(1) program.

October 4, 2023 UNIX