1Ppm3d User Manual(0) Ppm3d User Manual(0)
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6 ppm3d - convert two PPM images into an anaglyph (red/blue 3d glasses)
7 PPM
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11 ppm3d [-color] [-offset=horizontal_offset] leftppmfile rightppmfile
12 Deprecated optional 3rd argument: horizontal_offset
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17 This program is part of Netpbm(1).
18 ppm3d reads two PPM images as input and produces a PPM as output, with
20 the images overlapping by the specified number of pixels in blue-
21 green/red format. The idea is that if you look at the image with 3-D
22 glasses (glasses that admit only red through one eye and only green or
23 blue through the other), you see an image with depth. This is called
24 an anaglyph stereogram.
25 ppm3d can produce either of two kinds of anaglyph stereogram: mono‐
27 chrome or color. Use the -color option to choose.
28 In the monochrome version, ppm3d ignores any color (actually, chromi‐
30 nance) in the input images and produces a result which is monochrome.
31 Viewed through red-green glasses it is yellow, but without any other
32 color in the field, your brain tends to see it as grayscale.
33 In the color version, ppm3d generates a result which is close to the
35 color of the original. It's not great, though, due to the fact that
36 each eye necessarily cannot see the entire spectrum. Red and cyan
37 don't work well, but most other colors -- especially when heavily satu‐
38 rated -- come out quite well.
39 To view a color analgyph stereogram, you need glasses with a left lens
41 that admits only red light and a right lens that admits only blue and
42 green light. (The right lens may be called a cyan lens because that is
43 its pigment in white light; don't be misled into thinking that cyan is
44 the only color that gets through it). Your brain is wired so that even
45 though the components of light are coming in through different eyes,
46 they mix in your brain to form the same sensation as if you were look‐
47 ing at the combined light with both eyes.
48 The input PPMs must be the same dimensions.
50 To make a different kind of stereogram, use pamstereogram. That makes
52 a steregram that you view without special glasses, just by letting your
53 eyes unfocus so that each eye sees different parts of the image.
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57 The mandatory arguments are file names of the left and right input
58 images.
59 An optional third argument specifies the same thing as the value of the
61 -offset argument, but is deprecated because -offset is easier to use
62 and read. Before Netpbm 10.38 (March 2007), this third argument is the
63 only way to specify the offset.
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67 -offset=horizontal_offset
68 This option indicates the amount, in pixels, by which the left
69 and image is offset to the right of the right image in the out‐
70 put.
71 The effect of this option is to move the entire image forward
73 (positive numbers) or backward (negative numbers). With a zero
74 offset, the main subject of the picture appears in the plane of
75 the picture (i.e. if the image is projected on a screen, the
76 location of the screen). The main subject is the subject at the
77 location where the line of sight of the left camera intersects
78 the line of sight of the right camera -- the main subject
79 appears at the same location in both the left and right images.
80 Default is zero.
82 This option was new in Netpbm 10.38 (March 2007). Before that,
84 use the third argument instead. Also, before Netpbm 10.38 the
85 default is +30 pixels.
86 -color This option causes ppm3d to generate a color anaglyph stere‐
89 ogram. By default, it generates monochrome.
90 This option was new in Netpbm 10.38 (March 2007).
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97 pamstereogram(1) ppm(1)
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101 Copyright (C) 1993 by David K. Drum.
102netpbm documentation 20 February 2007 Ppm3d User Manual(0)