Summary edit

Image information edit

Portable Network Graphics image, 515 pixels wide, 3089 pixels high, 8 bits per sample, RGB with alpha channel, 3780 pixels per metre (96 pixels per inch) resolution, 1/2.2 (0.45455) gamma, sRGB with relative colorimetric rendering intent, background colour #000000. Created with The GIMP 2.2.8, Netpbm 10.27.0 and pngcrush 1.5.10 on Tuesday the 23rd of May 2006.

Technical notes edit

With a range of 0–3, the values for Red, Green and Blue (on the left side) can be off, one third, two thirds or full (intensity of 0, 1/3, 2/3, 1). Obviously, having recurring decimals, it would not be practical to draw those numbers in the image itself; and vulgar fractions would be too similar to the binary values to be worth it (the binary number converted to decimal and divided by 3 gives the intensity). The stepping should be upscaled to the target bit-depth, which in this image is 8 bits per sample, giving 0 (hexadecimal 00), 85 (55), 170 (AA) and 255 (FF). The values 84 (54), 168 (A8) and 252 (FC) you see ever so often are the result of doing, from a 6-bit value, left-shift + zero-fill instead of linear scaling or left bit replication:

101010 (2A) → 10101010 (AA) : correct value
101010 (2A) → 10101000 (A8) : rounding error

See also the section Sample depth scaling of ISO/IEC 15948:2003 (section 12.5 on the W3C edition).

Orthopraxy edit

For any PNG screenshot from MS-DOS that uses the IBM16 palette or a subset of it, ie any CGA or EGA image (but not VGA), it is recommended to add an sBIT (significant bits) chunk with a value of 2 for each of Red, Green and Blue. In addition, the colour values should be checked for accuracy and fixed if erroneous (see above for the most common inaccuracy).

Other versions edit

• Image:IBM16_Palette_Map-reduced.png is a reduced-colour version (no antialising, palette with only one transparency entry) for decoders that ignore the alpha channel or generally for where resources are short.

Licensing edit

I, the copyright holder of this work, hereby publish it under the following licenses:

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled GNU Free Documentation License.http://www.gnu.org/copyleft/fdl.htmlGFDLGNU Free Documentation Licensetruetrue

	This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.
	You are free: to share – to copy, distribute and transmit the work to remix – to adapt the work Under the following conditions: attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use. share alike – If you remix, transform, or build upon the material, you must distribute your contributions under the same or compatible license as the original.
	This licensing tag was added to this file as part of the GFDL licensing update.http://creativecommons.org/licenses/by-sa/3.0/CC BY-SA 3.0Creative Commons Attribution-Share Alike 3.0truetrue

This file is licensed under the Creative Commons Attribution-Share Alike 2.5 Generic, 2.0 Generic and 1.0 Generic license.

You are free:

• to share – to copy, distribute and transmit the work
• to remix – to adapt the work

Under the following conditions:

• attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
• share alike – If you remix, transform, or build upon the material, you must distribute your contributions under the same or compatible license as the original.

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