ThunderScan compression - Revision history

Jsummers at 19:31, 14 December 2019

2019-12-14T19:31:31Z

Jsummers: Updated links

2016-09-18T12:24:33Z

Updated links

Jsummers at 21:51, 11 November 2015

2015-11-11T21:51:10Z

Jsummers: Category:TIFF

2014-02-22T17:14:16Z

Category:TIFF

Jsummers: Formatting

2013-05-09T17:59:18Z

Formatting

Jsummers at 16:20, 8 May 2013

2013-05-08T16:20:59Z

Jsummers at 14:51, 20 April 2013

2013-04-20T14:51:45Z

Jsummers: Created page with "{{FormatInfo |formattype=electronic |subcat=Graphics }} == Overview == '''ThunderScan compression''', or '''ThunderScan RLE''', is a compressed image format for 4-bit grayscal..."

2013-04-20T14:44:55Z

Created page with "{{FormatInfo |formattype=electronic |subcat=Graphics }} == Overview == '''ThunderScan compression''', or '''ThunderScan RLE''', is a compressed image format for 4-bit grayscal..."

New page

{{FormatInfo
|formattype=electronic
|subcat=Graphics
}}
== Overview ==
'''ThunderScan compression''', or '''ThunderScan RLE''', is a compressed image format for 4-bit grayscale images. It can be used in [[TIFF]] files, and is identified by TIFF compression code 32809.

== Format ==
The compression scheme is pixel-oriented, and uses [[run-length encoding]] and [[delta encoding]].

Each coded byte represents one of four things, as indicated by the two highest bits:

00xxxxxx = A run of pixels whose colors are the same as that of the previous pixel
01xxxxxx = Three pixels whose colors are very similar to that of the previous pixel
10xxxxxx = Two pixels whose colors are very similar to that of the previous pixel
11xxxxxx = A single pixel of arbitrary color

== Software ==
* [http://www.remotesensing.org/libtiff/ libtiff] (read-only)

== Sample files ==
* [ftp://ftp.remotesensing.org/pub/libtiff/pics-3.8.0.tar.gz pics-3.8.0.tar.gz] → libtiffpic/text.tif

== Editors notes ==
Libtiff calls this format "the 4-bit compression algorithm used by the ThunderScan program", but we have not been able to confirm its origin. Nearly all the information about it comes from libtiff.

''ThunderScan'' is a scanner device for Apple II computers.
* [http://apple2online.com/web_documents/thunderscan_users_guide.pdf ThunderScan User's Guide]
* [http://apple2online.com/web_documents/thunderscan_iigs_software_guide.pdf ThunderScan GS Software Guide]

@@ Line 32: / Line 32: @@
 Libtiff calls this format "the 4-bit compression algorithm used by the ThunderScan program", but we have not been able to confirm its origin. Nearly all the information about it comes from libtiff.
-''ThunderScan'' is a scanner device for Apple II computers.
+Possibly-related things named ''ThunderScan'' include:
-* [http://apple2online.com/web_documents/thunderscan_users_guide.pdf ThunderScan User's Guide]
+* An image file format supported by old versions of [[Photoshop]] (including v1.0.1 - see the [https://computerhistory.org/blog/adobe-photoshop-source-code/ source code])
-* [http://apple2online.com/web_documents/thunderscan_iigs_software_guide.pdf ThunderScan GS Software Guide]
+* A scanner device for Apple II computers
 [[Category:Graphics]]
 [[Category:TIFF]]

← Older revision		Revision as of 17:14, 22 February 2014
Line 38:		Line 38:

	[[Category:Compression]]		[[Category:Compression]]
		+	[[Category:TIFF]]

← Older revision		Revision as of 14:51, 20 April 2013
Line 28:		Line 28:
	* [http://apple2online.com/web_documents/thunderscan_users_guide.pdf ThunderScan User's Guide]		* [http://apple2online.com/web_documents/thunderscan_users_guide.pdf ThunderScan User's Guide]
	* [http://apple2online.com/web_documents/thunderscan_iigs_software_guide.pdf ThunderScan GS Software Guide]		* [http://apple2online.com/web_documents/thunderscan_iigs_software_guide.pdf ThunderScan GS Software Guide]
		+
		+	[[Category:Compression]]

@@ Line 24: / Line 24: @@
 == Software ==
-* [http://www.remotesensing.org/libtiff/ libtiff] (read-only)
+* {{Libtiff}} (read-only)
 == Sample files ==
-* [ftp://ftp.remotesensing.org/pub/libtiff/pics-3.8.0.tar.gz pics-3.8.0.tar.gz] → libtiffpic/text.tif
+* [http://download.osgeo.org/libtiff/pics-3.8.0.tar.gz pics-3.8.0.tar.gz] → libtiffpic/text.tif
 == Editors' notes ==

@@ Line 1: / Line 1: @@
 {{FormatInfo
 |formattype=electronic
-|subcat=Graphics
+|subcat=Compression
 }}
 '''ThunderScan compression''', or '''ThunderScan RLE''', is a compressed image format for 4-bit grayscale images. It can be used in [[TIFF]] files, and is identified by TIFF compression code 32809.
 == Format ==
-The compression scheme is pixel-oriented, and uses [[run-length encoding]] and [[delta encoding]].
+The compression scheme is pixel-oriented, and uses [[run-length encoding]] and delta encoding.
 Each coded byte represents one of four things, as indicated by the two highest bits:
@@ Line 37: / Line 36: @@
 * [http://apple2online.com/web_documents/thunderscan_iigs_software_guide.pdf ThunderScan GS Software Guide]
-[[Category:Compression]]
+[[Category:Graphics]]
 [[Category:TIFF]]

@@ Line 11: / Line 11: @@
 Each coded byte represents one of four things, as indicated by the two highest bits:
-xxxxxx = A run of pixels whose colors are the same as that of the previous pixel
+{| class="wikitable"
-xxxxxx = Three pixels whose colors are very similar to that of the previous pixel
+! Byte value
-xxxxxx = Two pixels whose colors are very similar to that of the previous pixel
+! Interpretation
-xxxxxx = A single pixel of arbitrary color
+|-
 == Software ==