August 9, 2007 Edition

JPEG Compression Test

Allume, the people who make the Stuffit archiver have created a new compression algorithm that will losslessly compress JPEG files by an average of 30% (they claim). This algorithm will be part of the Stuffit 9 software.  I have done some benchmark testing to first see if their claim is legit and how well their compression performs against other lossless compression algorithms. This is not a test to see how well other image formats do compared to JPEG, but how well lossless compression algorithms can perform on already-compressed JPEG images. With the huge number of JPEG images on the web and from digital cameras, being able to compress JPEG pictures further, without losing any image quality may be of interest to many people.

The test computer used was a Pentium4 1.8GHz with 512MB of RAM running Windows 2000.

The three JPEG test files are:

Welcome Slashdot! If you use BZIP2 you might also be interested in my open source Parallel BZIP2 software.

	DSCN3974.jpg (National Art Gallery, Ottawa, Canada)
	File size: 1114198 bytes
	Resolution: 2048 x 1536
	Jpeg process: Baseline (Nikon Fine Compression)
	SHA-1 Hash: f6b3b306f213d3f7568696ed6d94d36e58b4ce1b

	DSCN4465.jpg (Golden Pagoda, Kyoto, Japan)
	File size: 694895 bytes
	Resolution: 2048 x 1536
	Jpeg process: Baseline (Nikon Normal Compression)
	SHA-1 Hash: 5f3d92f558d7cc2d850aa546ae287fa7b61f890d

	DSCN5081.jpg (AI Building, MIT, USA)
	File size: 516726 bytes
	Resolution: 2048 x 1536
	Jpeg process: Baseline (Nikon Fine Compression)
	SHA-1 Hash: 3dcf29223076c4acae5108f6d2fa04cd1ddc5e70

The test program sent to me by Allume is a beta version and not the final product so things could change for the commercial release. The test program they sent was a single Windows executable (.exe) that is 118,784 bytes in size and performs both compression and uncompression. The executable itself is not compressed and UPX would bring it down to about 53KB.  A newer version of the software (called b2 on this page) was sent to me and those results are now included.  This algorithm is now included in the Stuffit Deluxe 9 suite.

The test method used to show that the algorithm is real and no tricks were being used is described. I placed the compressor onto a floppy disk and copied the .exe file to Machine A and Machine B. Both machines have no way to communicate with each other and are not connected to any wired or wireless network. I used my Nikon Coolpix 3MP digital camera to generate JPEG files for use in the test. The three image files were copied to Machine A. They were not copied to and did not previously exist on Machine B. On Machine A, the SHA-1 hash of the 3 JPEG files were taken and the digests written down. The Allume software was used to individually compress the 3 JPEG files and sure enough they all got close to 30% compression. The compressed files only were copied to a floppy disk and then walked over to Machine B. They were then copied to Machine B and using the Allume executable already installed, the 3 JPEG files were uncompressed. The file sizes on Machine B matched the originals on Machine A which is a good start. The images were viewable in a JPEG reader as expected. Finally the SHA-1 hashes of the uncompressed files on Machine B were taken and confirmed to match the SHA-1 hashes of the original JPEG files on Machine A which means they are bit for bit identical. This is not a hoax, but the algorithm actually works.

The programs jpegtran, jpegoptim, jpeg-wizard2, and jpeg-ari all use "lossless" optimizations/transformations on the JPEG files and are therefore included in this test. Lossless in this case means that there is no loss of quality to the image but it is not possible to get back an identical (bit for bit) version of the original JPEG you started with. The other software in the test are true lossless compressors that can give back an identical uncompressed version of the JPEG you started with.  The tests listed as "Allume + jpegtran" means the jpeg file was first optimized with jpegtran and then compressed with the Allume algorithm.

Legend
+ - New program tested
B - Best compression (smallest compressed file)
F - Fastest compression time
Q - Quickest extraction time

	ACT 2.0 JPEG Test	DSCN3974.jpg
	Total Files Size (bytes):	1,114,198
	Name	Switches	Compress Time	Extract Time	Compressed Size	Compress Ratio
			(seconds)	(seconds)	(bytes)	(%)
B	Allume b2 + jpegtran	(none)	7.8	7.9	825,554	25.9
	Allume b2 + Jpegoptim	(none)	7.7	8.1	832,133	25.3
	Allume JPEG b2	(none)	7.9	8.1	832,139	25.3
	Stuffit Deluxe 9.0.0.17	JPEG smaller	4.7	4.5	834,053	25.1
	Stuffit Deluxe 9.0.0.17	JPEG smaller + Thumbnails	4.8	4.3	836,491	24.9
+	packJPG 2.2	(none)	4.1	4.2	873,261	21.6
	Stuffit Deluxe 9.0.0.17	JPEG fastest	2.1	2.1	876,552	21.3
	Stuffit Deluxe 9.0.0.17	JPEG fastest + Thumbnails	2.3	2.2	878,990	21.1
	packJPG 1.9a	(none)	5.9	6.2	908,695	18.4
	JPEG Wizard 2.4	PIC format	0.7	N/A	946,893	15.0
	jpeg-ari 28mar98	-arithmetic	0.7	0.9	949,274	14.8
	IJG jpegtran 6b	-optimize	0.4	N/A	1,082,948	2.8
	Jpegoptim 1.2.2	(none)	1.3	N/A	1,097,355	1.5
	bzip2 1.02	(none)	1.6	0.5	1,101,627	1.1
	7-Zip 3.13	PPMd	4.3	3.9	1,102,032	1.1
FQ	zip 2.3	-9j	0.2	0.1	1,104,866	0.8
	rar 3.42	-m5	1.7	0.1	1,107,336	0.6
	7-Zip 3.13	LZMA	2.6	0.4	1,113,492	0.1
	Best Compression:	Allume JPEG b2
	Fastest Compression:	zip 2.3
	Quickest Extraction:	zip 2.3

	ACT 2.0 JPEG Test	DSCN4465.jpg
	Total Files Size (bytes):	694,895
	Name	Switches	Compress Time	Extract Time	Compressed Size	Compress Ratio
			(seconds)	(seconds)	(bytes)	(%)
B	Allume b2 + jpegtran	(none)	5.7	5.8	518,046	25.4
	Stuffit Deluxe 9.0.0.17	JPEG smaller	3.2	3.0	523,266	24.7
	Allume b2 + Jpegoptim	(none)	5.8	5.8	524,982	24.5
	Allume JPEG b2	(none)	5.8	5.8	524,989	24.5
	Stuffit Deluxe 9.0.0.17	JPEG smaller + Thumbnails	3.2	3.0	526,184	24.3
+	packJPG 2.2	(none)	3.0	3.0	560,531	19.3
	Stuffit Deluxe 9.0.0.17	JPEG fastest	1.4	1.5	567,645	18.3
	Stuffit Deluxe 9.0.0.17	JPEG fastest + Thumbnails	1.7	1.6	570,563	17.9
	packJPG 1.9a	(none)	4.4	4.3	580,874	16.4
	JPEG Wizard 2.4	PIC format	0.8	N/A	606,305	12.7
	jpeg-ari 28mar98	-arithmetic	0.5	0.6	609,250	12.3
	IJG jpegtran 6b	-optimize	0.3	N/A	674,756	2.9
	bzip2 1.02	(none)	1.0	0.3	683,344	1.7
FQ	zip 2.3	-9j	0.1	0.1	683,462	1.6
	rar 3.42	-m5	1.2	0.1	685,283	1.4
	7-Zip 3.13	PPMd	2.5	2.4	687,425	1.1
	Jpegoptim 1.2.2	(none)	1.1	N/A	689,163	0.8
	7-Zip 3.13	LZMA	1.6	0.3	689,264	0.8
	Best Compression:	Allume b2 + jpegtran
	Fastest Compression:	zip 2.3
	Quickest Extraction:	zip 2.3

	ACT 2.0 JPEG Test	DSCN5081.jpg
	Total Files Size (bytes):	516,726
	Name	Switches	Compress Time	Extract Time	Compressed Size	Compress Ratio
			(seconds)	(seconds)	(bytes)	(%)
B	Allume b2 + jpegtran	(none)	5.7	5.7	359,865	30.4
	Allume b2 + Jpegoptim	(none)	5.7	5.8	364,916	29.4
	Allume JPEG b2	(none)	5.8	5.8	372,533	27.9
	Stuffit Deluxe 9.0.0.17	JPEG smaller	2.9	2.4	373,637	27.7
	Stuffit Deluxe 9.0.0.17	JPEG smaller + Thumbnails	3.0	2.6	376,270	27.2
+	packJPG 2.2	(none)	3.4	3.4	402,761	22.1
	Stuffit Deluxe 9.0.0.17	JPEG fastest	1.5	1.4	407,978	21.0
	Stuffit Deluxe 9.0.0.17	JPEG fastest + Thumbnails	1.4	1.5	410,611	20.5
	packJPG 1.9a	(none)	4.7	4.9	422,389	18.3
	JPEG Wizard 2.4	PIC format	0.9	N/A	453,745	12.2
	jpeg-ari 28mar98	-arithmetic	0.4	0.5	455,181	11.9
	IJG jpegtran 6b	-optimize	0.3	N/A	482,661	6.6
	Jpegoptim 1.2.2	(none)	2.4	N/A	487,781	5.6
	7-Zip 3.13	PPMd	2.0	1.8	504,718	2.3
Q	rar 3.42	-m5	0.8	0.1	505,296	2.2
F	zip 2.3	-9j	0.1	0.1	505,334	2.2
	bzip2 1.02	(none)	0.7	0.2	506,714	1.9
	7-Zip 3.13	LZMA	1.2	0.2	508,449	1.6
	Best Compression:	Allume JPEG b2
	Fastest Compression:	zip 2.3
	Quickest Extraction:	rar 3.42

Return to the ACT Home Page.