[magick-users] merged multiple jpeg files into multipage tiff: size grows, why?

[Zhang Weiwu]

Dear list:

This is my first time try convert(1). I did this:
$ convert 1329.jpg 1330.jpg -adjoin identity.tiff

The two images are here:
gopher://sdf.lonestar.org/I/users/weiwu/1329.jpg
gopher://sdf.lonestar.org/I/users/weiwu/1330.jpg

Both images are less then 300KB in size, however the converted tiff
image is as big as 1331KB. This is strange as tiff file is twice as big
as it should be. As compression method shouldn't been changed (still
JPEG inside the TIFF) I wonder how this comes to be and, is there a way
to generate tiff image less then 600KB? Thanks in advance!

I also tested the generated tiff image to make sure it's still in JPEG
compression:

zhangweiwu at joe:/tmp> identify -verbose identity.tiff 
Image: identity.tiff
  Format: TIFF (Tagged Image File Format)
  Class: DirectClass
  Geometry: 1090x682
  Type: TrueColor
  Endianess: MSB
  Colorspace: RGB
  Channel depth:
    Red: 8-bit
    Green: 8-bit
    Blue: 8-bit
  Channel statistics:
    Red:
      Min: 0 (0)
      Max: 255 (1)
      Mean: 210.407 (0.825124)
      Standard deviation: 56.3656 (0.221042)
    Green:
      Min: 0 (0)
      Max: 255 (1)
      Mean: 207.888 (0.815247)
      Standard deviation: 57.746 (0.226455)
    Blue:
      Min: 0 (0)
      Max: 255 (1)
      Mean: 218.063 (0.85515)
      Standard deviation: 59.2252 (0.232256)
  Colors: 217255
  Rendering intent: Undefined
  Resolution: 300x300
  Units: PixelsPerInch
  Filesize: 1.21981mb
  Interlace: None
  Background color: white
  Border color: rgb(223,223,223)
  Matte color: grey74
  Transparent color: black
  Page geometry: 1090x682+0+0
  Dispose: Undefined
  Iterations: 0
  Scene: 0 of 2
  Compression: JPEG
  Orientation: TopLeft
  Document: identity.tiff
  Signature: 7d39a85d2fd208b09bbdb7024626ff3b748fb54d05054133c7b93d881dde094a
  Software: ImageMagick 6.2.4 02/15/07 Q16 http://www.imagemagick.org
  Tainted: False
  Version: ImageMagick 6.3.0 11/27/06 Q16 http://www.imagemagick.org
Image: identity.tiff
  Format: TIFF (Tagged Image File Format)
  Class: DirectClass
  Geometry: 1084x676
  Type: TrueColor
  Endianess: MSB
  Colorspace: RGB
  Channel depth:
    Red: 8-bit
    Green: 8-bit
    Blue: 8-bit
  Channel statistics:
    Red:
      Min: 0 (0)
      Max: 255 (1)
      Mean: 215.469 (0.844978)
      Standard deviation: 55.8373 (0.21897)
    Green:
      Min: 0 (0)
      Max: 255 (1)
      Mean: 209.302 (0.820794)
      Standard deviation: 62.2949 (0.244294)
    Blue:
      Min: 0 (0)
      Max: 255 (1)
      Mean: 219.628 (0.861284)
      Standard deviation: 62.5139 (0.245153)
  Colors: 199496
  Rendering intent: Undefined
  Resolution: 300x300
  Units: PixelsPerInch
  Filesize: 1.21981mb
  Interlace: None
  Background color: white
  Border color: rgb(223,223,223)
  Matte color: grey74
  Transparent color: black
  Page geometry: 1084x676+0+0
  Dispose: Undefined
  Iterations: 0
  Scene: 1 of 2
  Compression: JPEG
  Orientation: TopLeft
  Document: identity.tiff
  Signature: 0b2550953bb2dd12eda81f4496f40c9127d46c0bdeb8aa14bc2775b055cd21b9
  Software: ImageMagick 6.2.4 02/15/07 Q16 http://www.imagemagick.org
  Tainted: False
  User time: 0.920u
  Elapsed time: 0:02
  Pixels per second: 715.607kb
  Version: ImageMagick 6.3.0 11/27/06 Q16 http://www.imagemagick.org


-- 
Zhang Weiwu
Real Softservice
http://www.realss.com
+86 592 2091112