Sixel - revision history

Dank at 20:48, 25 June 2021

2021-06-25T20:48:36Z

← Older revision		Revision as of 20:48, 25 June 2021
Line 58:		Line 58:
	* [https://github.com/saitoha/libsixel libsixel] is pretty complete		* [https://github.com/saitoha/libsixel libsixel] is pretty complete
	* [[Theory and Practice of Sprixels]]		* [[Theory and Practice of Sprixels]]

			[[CATEGORY: Terminals]]

Dank: /* See also */

2021-04-01T15:27:39Z

Dank: link to dickey

2021-03-24T18:53:19Z

link to dickey

← Older revision		Revision as of 18:53, 24 March 2021
Line 1:		Line 1:
	Sixel ("six pixels") does not appear to have any true, up-to-date "standard". It seems to have been introduced on DEC printers, and made its first glass appearance on the VT125, though the [http://www.vt100.net/docs/vt3xx-gp/chapter14.html VT3xx] documentation gets the most play (the VT340 appears to have been the first terminal which could sensibly scroll pixel graphics). A single sixel combines a set of programmable color registers with a vertical stack of six pixels; a sixel sprite (sprixel?) is MxN pixels where N is a multiple of 6. It is probably the most widely implemented method of pixel graphics for terminal emulators ([https://sw.kovidgoyal.net/kitty/graphics-protocol.html kitty] has its own protocol, as does [http://www.asmeurer.com/iterm2-tools/images.html ITerm2]). [https://en.wikipedia.org/wiki/ReGIS ReGIS] is a similar method for vector graphics. A single horizontal strip of sixels is a "band"; a sprixel has one or more bands.		Sixel ("six pixels") does not appear to have any true, up-to-date "standard" (Thomas Dickey's [https://invisible-island.net/xterm/ctlseqs/ctlseqs.html XTerm Control Sequences] document is probably the closest thing). It seems to have been introduced on DEC printers, and made its first glass appearance on the VT125, though the [http://www.vt100.net/docs/vt3xx-gp/chapter14.html VT3xx] documentation gets the most play (the VT340 appears to have been the first terminal which could sensibly scroll pixel graphics). A single sixel combines a set of programmable color registers with a vertical stack of six pixels; a sixel sprite (sprixel?) is MxN pixels where N is a multiple of 6. It is probably the most widely implemented method of pixel graphics for terminal emulators ([https://sw.kovidgoyal.net/kitty/graphics-protocol.html kitty] has its own protocol, as does [http://www.asmeurer.com/iterm2-tools/images.html ITerm2]). [https://en.wikipedia.org/wiki/ReGIS ReGIS] is a similar method for vector graphics. A single horizontal strip of sixels is a "band"; a sprixel has one or more bands.

	Sixels are specified using only printable ASCII characters, and are thus 7-bit clean.		Sixels are specified using only printable ASCII characters, and are thus 7-bit clean.

Dank: /* Syntax */

2021-03-24T18:52:30Z

Syntax

← Older revision		Revision as of 18:52, 24 March 2021
Line 26:		Line 26:
	Each register is specified with a type ("1" for HSL, "2" for RGB) and three components, each between 0 and 100 inclusive. Assuming 8bpc RGB, every 2.6 bits of component get squashed to 1.		Each register is specified with a type ("1" for HSL, "2" for RGB) and three components, each between 0 and 100 inclusive. Assuming 8bpc RGB, every 2.6 bits of component get squashed to 1.

	The <tt>privateColorRegisters<tt> resource (default: "true") determines whether each sixel escape sequence controls its own distinct color registers, or whether they're shared by all sprixels.		The <tt>privateColorRegisters</tt> resource (default: "true") determines whether each sixel escape sequence controls its own distinct color registers, or whether they're shared by all sprixels.

	==Complexifiers==		==Complexifiers==

Dank: /* Color registers */

2021-03-21T04:42:02Z

Color registers

← Older revision		Revision as of 04:42, 21 March 2021
Line 25:		Line 25:

	Each register is specified with a type ("1" for HSL, "2" for RGB) and three components, each between 0 and 100 inclusive. Assuming 8bpc RGB, every 2.6 bits of component get squashed to 1.		Each register is specified with a type ("1" for HSL, "2" for RGB) and three components, each between 0 and 100 inclusive. Assuming 8bpc RGB, every 2.6 bits of component get squashed to 1.

			The <tt>privateColorRegisters<tt> resource (default: "true") determines whether each sixel escape sequence controls its own distinct color registers, or whether they're shared by all sprixels.

	==Complexifiers==		==Complexifiers==

Dank: /* Detecting support */

2021-03-14T11:13:53Z

Detecting support

← Older revision		Revision as of 11:13, 14 March 2021
Line 33:		Line 33:

	==Detecting support==		==Detecting support==
	''~~'FIXME'''~~		<tt>Send Device Attributes</tt> can be used to detect Sixel support. Send <tt>CSI Ps c</tt>. If the VT220-level reply contains a '4', sixel graphics are supported.
	===Detecting details===		===Detecting details===
	<tt>XTSMGRAPHICS</tt> can be used to set and retrieve Sixel-related configuration, if Sixel is supported. Send <tt>CSI ? Pi ; Pa ; Pv S</tt> where		<tt>XTSMGRAPHICS</tt> can be used to set and retrieve Sixel-related configuration, if Sixel is supported. Send <tt>CSI ? Pi ; Pa ; Pv S</tt> where

Dank: /* Detecting details */

2021-03-14T11:11:10Z

Detecting details

← Older revision		Revision as of 11:11, 14 March 2021
Line 43:		Line 43:
	* Pa == 4, read maximum value		* Pa == 4, read maximum value
	For color registers, the maximum value is the absolute maximum supported by the application. For geometry, the current value is affected by current window geometry in addition to configuration.		For color registers, the maximum value is the absolute maximum supported by the application. For geometry, the current value is affected by current window geometry in addition to configuration.

	===Known support===		===Known support===
	* <tt>xterm</tt> supports scrolling sprixels when compiled with <tt>--enable-sixel-graphics</tt>		* <tt>xterm</tt> supports scrolling sprixels when compiled with <tt>--enable-sixel-graphics</tt>

Dank: /* Detecting support */

2021-03-14T10:46:45Z

Detecting support

← Older revision		Revision as of 10:46, 14 March 2021
Line 34:		Line 34:
	==Detecting support==		==Detecting support==
	'''FIXME'''		'''FIXME'''
			===Detecting details===
			<tt>XTSMGRAPHICS</tt> can be used to set and retrieve Sixel-related configuration, if Sixel is supported. Send <tt>CSI ? Pi ; Pa ; Pv S</tt> where
			* Pi == 1, color registers
			* Pi == 2, maximum geometry
			* Pa == 1, read
			* Pa == 2, reset to default
			* Pa == 3, set to Pv
			* Pa == 4, read maximum value
			For color registers, the maximum value is the absolute maximum supported by the application. For geometry, the current value is affected by current window geometry in addition to configuration.
	===Known support===		===Known support===
	* <tt>xterm</tt> supports scrolling sprixels when compiled with <tt>--enable-sixel-graphics</tt>		* <tt>xterm</tt> supports scrolling sprixels when compiled with <tt>--enable-sixel-graphics</tt>

Dank: /* Syntax */

2021-03-07T18:55:56Z

Syntax

← Older revision		Revision as of 18:55, 7 March 2021
Line 17:		Line 17:

	Bands are separated by hyphens ('-'). Return to the start of a band without moving to the next one (i.e. to draw another color) with '$'. The same number of sixels ought be provided for each color used in a band (but they may of course be the empty sixel). For each sixel, determine which of the six pixels 0..5 (0 on the top, 5 on the bottom) match the color, and and for each pixel N, add 2ⁿ. The result will be between 0 and 63, inclusive. Add 63 to this total; the sixel is the corresponding ASCII character (between 63 and 126, inclusive). When a sixel is repeated four or more times in a row, use "!n" to runlength encode the series.		Bands are separated by hyphens ('-'). Return to the start of a band without moving to the next one (i.e. to draw another color) with '$'. The same number of sixels ought be provided for each color used in a band (but they may of course be the empty sixel). For each sixel, determine which of the six pixels 0..5 (0 on the top, 5 on the bottom) match the color, and and for each pixel N, add 2ⁿ. The result will be between 0 and 63, inclusive. Add 63 to this total; the sixel is the corresponding ASCII character (between 63 and 126, inclusive). When a sixel is repeated four or more times in a row, use "!n" to runlength encode the series.

			If a given pixel is unspecified (i.e. no band includes the pixel), the behavior is dependent on whether the Set Raster Attributes control sequence has been emitted. If it has, unspecified pixels are drawn with Color Register 0. If it has not, they are not touched. For transparency with regards to existing material, then, Set Raster Attributes must not be used.

	===Color registers===		===Color registers===

Dank at 18:28, 7 March 2021

2021-03-07T18:28:23Z

← Older revision		Revision as of 18:28, 7 March 2021
Line 7:		Line 7:
	==Syntax==		==Syntax==
	Before emitting a sprixel, the terminal must first be put into the appropriate mode via "\ePq" ('''FIXME''' details on 8-bit, start params). Properly exit the mode with "\e\\" ('''FIXME''' again 8-bit). '''FIXME what about \e[?80h?'''		Before emitting a sprixel, the terminal must first be put into the appropriate mode via "\ePq" ('''FIXME''' details on 8-bit, start params). Properly exit the mode with "\e\\" ('''FIXME''' again 8-bit). '''FIXME what about \e[?80h?'''

			The mode switch may be followed by an optional quartet of parameters, separated by semicolons:

			<tt>AspectX;AspectY;LenX;LenY</tt>

			I'm not yet completely sure of the effect of these parameters '''FIXME'''.

	Color registers precede the band data ''en bloc''. Each color register takes the form "#N;T;a;b;c" where N is the register and T is the type (see below).		Color registers precede the band data ''en bloc''. Each color register takes the form "#N;T;a;b;c" where N is the register and T is the type (see below).

← Older revision		Revision as of 15:27, 1 April 2021
Line 57:		Line 57:
	* [[Notcurses]] supports sixel intermingled with standard TUI elements		* [[Notcurses]] supports sixel intermingled with standard TUI elements
	* [https://github.com/saitoha/libsixel libsixel] is pretty complete		* [https://github.com/saitoha/libsixel libsixel] is pretty complete
			* [[Theory and Practice of Sprixels]]