GROB

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|released=~1990
 
|released=~1990
 
}}
 
}}
'''GROB''' is a bi-level raster graphics format associated with HP-48 and HP-49 series calculators.
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'''GROB''' is a (usually) bi-level raster graphics format associated with HP-48 and HP-49 series calculators.
  
 
There are two ways to encode a GROB image: "binary" and "ASCII". Sometimes, GROB images are also [[ASCII Encoded HP 48 Object|ASC-encoded]].
 
There are two ways to encode a GROB image: "binary" and "ASCII". Sometimes, GROB images are also [[ASCII Encoded HP 48 Object|ASC-encoded]].
  
== Format ==
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== Format details ==
 
Binary format has an 18-byte header, followed by the pixel data.
 
Binary format has an 18-byte header, followed by the pixel data.
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=== Grayscale images ===
 +
Although the format only really supports bi-level images, some images are intended to be interpreted as grayscale with 2 bits/pixel (or perhaps more). The physical image consists of the bit-planes stacked vertically. Unfortunately, there does not seem to be any way to detect whether this is the case.
  
 
== Identification ==
 
== Identification ==
A binary GROB file begins with "<code>HPHP48</code>" or "<code>HPHP49</code>", and has bytes <code>1E 2B</code> at offset 8.
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A binary GROB file begins with "{{magic|HPHP48}}" or "{{magic|HPHP49}}", and has bytes {{magic|1E 2B}} at offset 8.
  
ASCII format apparently begins with "<code>GROB </code>". An ASCII GROB might be embedded inside a script, or preceded by a "<code>%%HP</code>" header line, so it won't necessarily start at the beginning of the file.
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ASCII format apparently begins with "{{magic|GROB }}". An ASCII GROB might be embedded inside a script, or preceded by a "{{magic|%%HP}}" header line, so it won't necessarily start at the beginning of the file.
  
 
== Software ==
 
== Software ==
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== Sample files ==
 
== Sample files ==
 
=== Binary ===
 
=== Binary ===
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* http://cd.textfiles.com/hhot/CALCUL~5/HP48G/GRAPHICS/ ...
 
* [http://cd.textfiles.com/blackphiles/PHILES/HP48_1/GROBS1.ZIP GROBS1.ZIP], [http://cd.textfiles.com/blackphiles/PHILES/HP48_1/GROBS2.ZIP GROBS2.ZIP]
 
* [http://cd.textfiles.com/blackphiles/PHILES/HP48_1/GROBS1.ZIP GROBS1.ZIP], [http://cd.textfiles.com/blackphiles/PHILES/HP48_1/GROBS2.ZIP GROBS2.ZIP]
 
* [http://www.hpcalc.org/details.php?id=4228 grobs49.zip]
 
* [http://www.hpcalc.org/details.php?id=4228 grobs49.zip]

Revision as of 11:57, 22 September 2017

File Format
Name GROB
Ontology
Extension(s) .grb, .gro, others
Released ~1990

GROB is a (usually) bi-level raster graphics format associated with HP-48 and HP-49 series calculators.

There are two ways to encode a GROB image: "binary" and "ASCII". Sometimes, GROB images are also ASC-encoded.

Contents

Format details

Binary format has an 18-byte header, followed by the pixel data.

Grayscale images

Although the format only really supports bi-level images, some images are intended to be interpreted as grayscale with 2 bits/pixel (or perhaps more). The physical image consists of the bit-planes stacked vertically. Unfortunately, there does not seem to be any way to detect whether this is the case.

Identification

A binary GROB file begins with "HPHP48" or "HPHP49", and has bytes 1E 2B at offset 8.

ASCII format apparently begins with "GROB ". An ASCII GROB might be embedded inside a script, or preceded by a "%%HP" header line, so it won't necessarily start at the beginning of the file.

Software

Sample files

Binary

ASCII

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