Results 1 to 3 of 3

Thread: zpaq grayscale compression (intro to zpaql)

  1. #1
    Member
    Join Date
    May 2015
    Location
    SF
    Posts
    4
    Thanks
    0
    Thanked 14 Times in 4 Posts

    zpaq grayscale compression (intro to zpaql)

    Hi all

    Longtime lurker, first time poster. I recently spent a number of days getting up to speed on zpaql and how to write a zpaq image compression config for grayscale images. I could not find any information online about how to actually get started writing a zpaql config for 2D image compression, so I wrote up an intro on my blog:

    http://www.modejong.com/blog/post15_...ale/index.html

    With this config lena512.pgm would compress down to 138 kB with minimal CPU usage (for a zpaq configuration).

    cheers
    Mo

  2. Thanks (3):

    Bulat Ziganshin (13th May 2015),Matt Mahoney (13th May 2015),thometal (13th May 2015)

  3. #2
    Member
    Join Date
    Jun 2008
    Location
    G
    Posts
    377
    Thanks
    26
    Thanked 23 Times in 16 Posts
    Nice, would it only possible to include custom written cfg into zpaq and not only in zpaqd which doesnt support the deduplication...........
    Last edited by thometal; 13th May 2015 at 22:30.

  4. #3
    Expert
    Matt Mahoney's Avatar
    Join Date
    May 2008
    Location
    Melbourne, Florida, USA
    Posts
    3,257
    Thanks
    307
    Thanked 797 Times in 489 Posts
    Archives created with zpaqd can be decompressed with zpaq. zpaqd archives are streaming (no dedupe), but you can mix types by appending streaming to journaling and vice versa.

    Also, keep in mind in the comparison that bmp_j4.cfg is compressing a color image, which is 3x larger. But it is a nice tutorial to writing ZPAQL custom code.

Similar Threads

  1. ZPAQ GUI
    By thometal in forum Data Compression
    Replies: 32
    Last Post: 29th January 2018, 01:17
  2. ZPAQ FS
    By barrycarter in forum Data Compression
    Replies: 0
    Last Post: 10th March 2015, 01:43
  3. jpeg to zpaq lossy compression
    By toi007 in forum Data Compression
    Replies: 11
    Last Post: 24th January 2013, 03:20
  4. the zero redunduncy in zpaq normal jpg compression
    By toi007 in forum Data Compression
    Replies: 3
    Last Post: 16th August 2012, 23:40
  5. Welcome/Intro
    By encode in forum Forum Archive
    Replies: 1
    Last Post: 13th May 2006, 23:25

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •