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greg |
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.TH NORMTIFF 1 2/25/99 RADIANCE |
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.SH NAME |
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normtiff - tone-map and convert RADIANCE picture or SGILOG TIFF to RGB TIFF |
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.SH SYNOPSIS |
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.B normtiff |
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[ |
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.B options |
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] |
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.B input |
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.B output.tif |
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.SH DESCRIPTION |
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.I Normtiff |
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prepares a Radiance picture or SGILOG (high dynamic range) TIFF |
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for output to a display or hard copy device. |
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If the dynamic range of the scene exceeds that of the display (as is |
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usually the case), |
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.I normtiff |
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will compress the dynamic range of the picture such that both |
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dark and bright regions are visible. |
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In addition, certain limitations in human vision may be mimicked in |
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order to provide an appearance similar to the experience one might |
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have in the actual scene. |
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.PP |
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Output is always an uncompressed RGB TIFF, which must be named |
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on the command line along with the input file. |
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If the input file has a ".tif" or ".tiff" extension, |
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.I normtiff |
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attempts to read it as a TIFF. |
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Otherwise, |
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.I normtiff |
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first tries opening it as a RADIANCE picture, only opening it |
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as a TIFF if it fails header inspection. |
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(See the |
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.I getinfo(1) |
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program.)\0 |
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If the input is neither a RADIANCE picture nor an SGILOG-encoded TIFF, |
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the program reports an error and exits. |
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.PP |
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The following command line options are understood. |
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Since this program is very similar to |
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.I pcond(1), |
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several of the switches are identical. |
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.TP 10n |
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.BR -b |
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Toggle 8-bit black and white (grayscale) TIFF output. |
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If the input is a 16-bit SGILOG luminance-only TIFF, this switch is |
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automatically selected. |
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Otherwise, the output defaults to 24-bit RGB. |
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.TP |
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.BR -h |
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Mimic human visual response in the output. |
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The goal of this process is to produce output that correlates |
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strongly with a person's subjective impression of a scene. |
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This switch turns on both the |
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.I \-s |
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and |
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.I \-c |
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switches, described below. |
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.TP |
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.BR -s |
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Toggle the use of the human contrast sensitivity function in determining the |
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exposure for the image. |
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A darker scene will have relatively lower exposure with lower |
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contrast than a well-lit scene. |
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.TP |
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.BR -c |
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Toggle mesopic color correction. |
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If parts of the image are in the mesopic or scotopic range where |
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the cone photoreceptors lose their efficiency, this switch will |
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cause a corresponding loss of color visibility in the output and a |
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shift to a scotopic (blue-dominant) response function. |
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.TP |
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.BR -l |
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Toggle the use of a linear response function versus the standard dynamic |
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range compression algorithm. |
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This may make some parts of the resulting image too |
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dark or too bright to see. |
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.TP |
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.BI -u \ Ldmax |
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Specifies the top of the luminance range for the target output device. |
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That is, the luminance (in candelas/m^2) for an output pixel value |
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of (R,G,B)=(255,255,255). |
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This parameter affects tone mapping only when the |
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.I \-s |
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switch is on. |
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The default value is 100 cd/m^2. |
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.TP |
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.BI -d \ Lddyn |
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Specifies the dynamic range for the target output device, which is |
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the ratio of the maximum and minimum usable display luminances. |
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The default value is 32, which is typical for CRT monitors. |
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.TP |
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.BI -p " xr yr xg yg xb yb xw yw" |
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Specifies the RGB primaries for the target output device. |
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These are the 1931 CIE (x,y) chromaticity values for red, green, |
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blue and white, respectively. |
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.TP |
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.BI -g \ gamma |
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Specifies the output device gamma correction value. |
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The default value is 2.2, which is appropriate for most CRT monitors. |
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(A value of 1.8 is common in color prepress and color printers.)\0 |
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.SH EXAMPLES |
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To convert a RADIANCE picture to an 8-bit grayscale TIFF: |
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.IP "" .2i |
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normtiff -b scene.pic sceneb.tif |
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.PP |
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To condition an SGILOG TIFF for a particular film recorder with |
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known color primaries, dynamic range and gamma response: |
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.IP "" .2i |
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pcond -d 50 -g 2.5 -p .580 .340 .281 .570 .153 .079 .333 .333 orig.tif filmrgb.tif |
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.PP |
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To simulate human visual response on a monitor with known maximum luminance: |
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.IP "" .2i |
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normtiff -h -u 80 scene.pic sceneh.tif |
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.SH REFERENCE |
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Greg Ward Larson, Holly Rushmeier, Christine Piatko, |
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``A Visibility Matching Tone Reproduction Operator for High Dynamic Range |
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Scenes,'' |
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.I "IEEE Transactions on Visualization and Computer Graphics", |
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December 1997. |
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.PP |
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http://positron.cs.berkeley.edu/gwlarson/pixformat/ |
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.SH AUTHOR |
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Greg Ward Larson |
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.SH ACKNOWLEDGMENT |
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This work was supported by Silicon Graphics, Inc. |
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.SH "SEE ALSO" |
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getinfo(1), pcond(1), pflip(1), |
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pvalue(1), protate(1), ra_xyze(1), rpict(1), ximage(1) |
