Palettes
From Just Solve the File Format Problem
(Difference between revisions)
(→Structure) |
|||
| Line 17: | Line 17: | ||
Game palettes often comprise a the following chunks of data: | Game palettes often comprise a the following chunks of data: | ||
| − | * The '''palette''' itself, usually containing 256 ''swatches'', 3 bytes per color totaling 768 bytes in length. The 256 limit corresponds to the ''8bpp mode'' (or ''256 color mode'') limitations of personal computers of the time. | + | * The '''palette''' itself, usually containing 256 ''swatches'', 3 bytes per ''color component'' totaling 768 bytes in length. The 256 limit corresponds to the ''8bpp mode'' (or ''256 color mode'') limitations of personal computers of the time. |
* Any number of '''Blending tables''', which store pre-computed transformations on a palette, such as shading or blending. The results refer back to an index in the palette itself. | * Any number of '''Blending tables''', which store pre-computed transformations on a palette, such as shading or blending. The results refer back to an index in the palette itself. | ||
The '''palette''': | The '''palette''': | ||
| − | * Palettes are often stored as '''tuples''' (1 byte for the red, green and blue | + | * Palettes are often stored as '''tuples''' (1 byte for the red, green and blue component in sequence) or in '''planes''' (1 byte for the red component for each swatch, then 1 byte for the green, then 1 byte for the blue). Palettes are often loaded directly into memory, and as such, their format usually matches the format needed by the underlying hardware. |
* Whilst <code>RGB</code> component ordering is conventional, the components are sometimes ordered differently. | * Whilst <code>RGB</code> component ordering is conventional, the components are sometimes ordered differently. | ||
* If the palette appears dimmer than expected, it might be using less bits per byte in one or all components. It was common to store components using 6-bits (0-63). These would need to be multiplied by 4 to map the components back to the expected range of 0-255. | * If the palette appears dimmer than expected, it might be using less bits per byte in one or all components. It was common to store components using 6-bits (0-63). These would need to be multiplied by 4 to map the components back to the expected range of 0-255. | ||
* Often, the palette is the first chunk of data within the file. | * Often, the palette is the first chunk of data within the file. | ||
Revision as of 12:49, 11 January 2023
A palette is, at its simplest, a lookup-table of colors with their corresponding index that is utilized when displaying computer graphics. Palettes are either:
- Defined by the hardware (i.e. the palette used by the graphics hardware of the NES) or
- Embedded within a file-format or specific to a piece of software (such as a palette embedded within a GIF or 8-bit PNG)
Whilst palettes are common across all media, they are particularly common in games.
Game palettes
Early game formats would often make use of a palette for two primary reasons:
- The historical limits of graphics hardware meant that a full-spectrum of colors was not feasible or necessary.
- Palette's allow for greater compression of in-game assets and less processing-time when loading these assets or displaying them on screen.
Structure
Game palettes often comprise a the following chunks of data:
- The palette itself, usually containing 256 swatches, 3 bytes per color component totaling 768 bytes in length. The 256 limit corresponds to the 8bpp mode (or 256 color mode) limitations of personal computers of the time.
- Any number of Blending tables, which store pre-computed transformations on a palette, such as shading or blending. The results refer back to an index in the palette itself.
The palette:
- Palettes are often stored as tuples (1 byte for the red, green and blue component in sequence) or in planes (1 byte for the red component for each swatch, then 1 byte for the green, then 1 byte for the blue). Palettes are often loaded directly into memory, and as such, their format usually matches the format needed by the underlying hardware.
- Whilst
RGBcomponent ordering is conventional, the components are sometimes ordered differently. - If the palette appears dimmer than expected, it might be using less bits per byte in one or all components. It was common to store components using 6-bits (0-63). These would need to be multiplied by 4 to map the components back to the expected range of 0-255.
- Often, the palette is the first chunk of data within the file.
