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8-bit packing

A packed color is a single integer — handy for storing a color in one BIGINT column, sending it to a frontend, or matching a format another tool already uses. Packing converts to sRGB, clamps into gamut, quantizes each channel and alpha to 8 bits, then puts the four bytes in the chosen order. Unpacking reverses it and always returns an srgb color.

plt_pack(color) and plt_pack(color, order)​

Signature: plt_pack(color plt_color) -> BIGINT Signature: plt_pack(color plt_color, order VARCHAR) -> BIGINT

The one-argument form uses argb, palette's default, which makes the low 24 bits read like a #rrggbb value. The two-argument form takes argb, rgba, abgr or bgra.

SELECT plt_pack(plt_srgb(1, 0.5, 0)) AS argb,
       plt_pack(plt_srgb(1, 0.5, 0), 'rgba') AS rgba,
       plt_pack(plt_srgb(1, 0.5, 0), 'bgra') AS bgra;
 
SELECT plt_pack_orders() AS orders;

Alpha is part of the integer. An opaque color has 255 in the alpha byte, a half-transparent one has 128:

SELECT plt_pack(plt_color('srgb', 1, 0.5, 0, 1)) AS opaque,
       plt_pack(plt_color('srgb', 1, 0.5, 0, 0.5)) AS half_transparent;

Packing works from any space; the conversion to sRGB is implicit:

SELECT plt_pack(plt_oklch(0.7, 0.1, 120)) AS from_oklch,
       plt_pack(plt_lab(50, 200, 200)) AS out_of_gamut_clamped;

plt_unpack(value) and plt_unpack(value, order)​

Signature: plt_unpack(value BIGINT) -> plt_color Signature: plt_unpack(value BIGINT, order VARCHAR) -> plt_color

The inverse. The order must match the one used to pack. Values outside 0..4294967295 are an error; an unknown order is too.

SELECT plt_to_hex(plt_unpack(plt_pack(plt_srgb(1, 0.5, 0)))) AS round_trip,
       plt_unpack(plt_pack(plt_srgb(1, 0.5, 0))) AS unpacked;
 
SELECT plt_to_hex(plt_unpack(plt_pack(plt_srgb(1, 0.5, 0), 'rgba'), 'rgba')) AS rgba_round_trip,
       plt_to_hex(plt_unpack(plt_pack(plt_color('srgb', 1, 0.5, 0, 0.5), 'bgra'), 'bgra')) AS with_alpha;

The round trip is lossy by design: components come back as multiples of 1/255. Use it for storage and transport, not as an alternative to plt_convert.

SELECT plt_components(plt_srgb(0.2, 0.4, 0.6)) AS original,
       plt_components(plt_unpack(plt_pack(plt_srgb(0.2, 0.4, 0.6)))) AS after_round_trip;
 
SELECT plt_unpack(4294967296);
 
SELECT plt_unpack(0, 'rgb');

plt_pack_orders()​

Signature: plt_pack_orders() -> VARCHAR[]

The four channel orders: argb, rgba, abgr, bgra. Names are case-insensitive, and - or a space counts as _.