Tiff to PNG speed, and advice on Q16 vs Q8

Hello,

As mentioned in quite a few other posts, convert can be slow
in converting 
images between one format and another, depending on setup. I
am experiencing 
very slow processing. (Admittedly I'm working on an
underpowered laptop, 
which does not help).

Can I get some advice? I have about 1000 tiff images, of
about 500KB each, so 
not vast as far as tiffs are concerned. They are monochrome
from microfilm. I 
want to convert them to pngs suitable for website display -
so resize and 
then convert them. 

Unfortunately the files were converted on some proprietary
Windows based 
scanning platform - opening them in the GIMP crashes KDE!
However they are 
not corrupted. I have put some version info at the end of
this message. Note 
the 'unknown field' report at the end, which every image
has.

The advice I need is:
Will using Q8 rather than Q16 decrease the quality of the
resulting image?
Would resizing first and then converting be better/quicker
than doing in one 
convert command?
If I want to use Q8, am I going to have to compile it?!
Would I have to 
unistall Q16 first? I'd rather apt-get, but I can't see it
in my repos.

I guess I could try this in DOS, but I really don't want
to!

Many thanks
RT

BASH# imageidentify -verbose Image 0106.tif
Image 0106.tif TIFF 8768x6528 DirectClass 377kb 2.120u 1:50
Image: Image 0106.tif
  Format: TIFF (Tagged Image File Format)
  Geometry: 8768x6528
  Class: DirectClass
  Type: Bilevel
  Endianess: MSB
  Colorspace: Gray
  Channel depth:
    Gray: 1-bits
  Channel statistics:
    Gray:
      Min: 0 (0)
      Max: 1 (1)
      Mean: 0.703899 (0.703899)
      Standard deviation: 0.456536 (0.456536)
  Colors: 2
  Histogram:
  16948097: (  0,  0,  0)       black
  40289407: (255,255,255)       white
  Rendering-intent: Undefined
  Resolution: 300x300
  Units: PixelsPerInch
  Filesize: 377kb
  Interlace: None
  Background Color: white
  Border Color: #DFDFDF
  Matte Color: grey74
  Dispose: Undefined
  Iterations: 0
  Compression: Group4
  Orientation: LeftBottom
  Make: Wicks and Wilson
  Model: Wicks and Wilson Rollfilm Scanner
  Signature:
6c1866aefbf7ea8a979de406e6659a540dc0df115167de95efb251274bdd
1173
  Software: Wicks and Wilson TIFF VER 1.0
  Timestamp: 2007:03:05 09:31:06
  Tainted: False
  Version: ImageMagick 6.2.4 02/15/07 Q16 http://www.imagemagick.org

identify: Image 0106.tif: unknown field with tag 32961
(0x80c1) encountered. 
`TIFFReadDirectory'.
 conversion?






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On approximately 4/6/2007 8:10 AM, came the following
characters from 
the keyboard of Roland Tanner:
> Hello,
>
> As mentioned in quite a few other posts, convert can be
slow in converting 
> images between one format and another, depending on
setup. I am experiencing 
> very slow processing. (Admittedly I'm working on an
underpowered laptop, 
> which does not help).
>
> Can I get some advice? I have about 1000 tiff images,
of about 500KB each, so 
> not vast as far as tiffs are concerned. They are
monochrome from microfilm. I 
> want to convert them to pngs suitable for website
display - so resize and 
> then convert them. 
>
> Unfortunately the files were converted on some
proprietary Windows based 
> scanning platform - opening them in the GIMP crashes
KDE! However they are 
> not corrupted. I have put some version info at the end
of this message. Note 
> the 'unknown field' report at the end, which every
image has.
>
> The advice I need is:
> Will using Q8 rather than Q16 decrease the quality of
the resulting image?
>   

Q8 would not decrease the quality of a monochrome image...
it seems 
(from the identify below) that by monochrome you are
referring to a 
2-color, bilevel image.  Because that has a bit depth of 1,
using a bit 
depth of even 8 is overkill, but that is the smallest than
IM offers. Q8 
would save roughly half the memory requirements of Q16, so
it could 
provide a significant speedup, especially if the resulting
memory 
requirements can be satisfied by RAM.

> Would resizing first and then converting be
better/quicker than doing in one 
> convert command?
>   

Doubtful.


> If I want to use Q8, am I going to have to compile it?!
Would I have to 
> unistall Q16 first? I'd rather apt-get, but I can't see
it in my repos.
>   

Can't help here, I only use Windows, at present.

> I guess I could try this in DOS, but I really don't
want to!
>
> Many thanks
> RT
>
> BASH# imageidentify -verbose Image 0106.tif
> Image 0106.tif TIFF 8768x6528 DirectClass 377kb 2.120u
1:50
> Image: Image 0106.tif
>   Format: TIFF (Tagged Image File Format)
>   Geometry: 8768x6528
>   Class: DirectClass
>   Type: Bilevel
>   Endianess: MSB
>   Colorspace: Gray
>   Channel depth:
>     Gray: 1-bits
>   Channel statistics:
>     Gray:
>       Min: 0 (0)
>       Max: 1 (1)
>       Mean: 0.703899 (0.703899)
>       Standard deviation: 0.456536 (0.456536)
>   Colors: 2
>   Histogram:
>   16948097: (  0,  0,  0)       black
>   40289407: (255,255,255)       white
>   Rendering-intent: Undefined
>   Resolution: 300x300
>   Units: PixelsPerInch
>   Filesize: 377kb
>   Interlace: None
>   Background Color: white
>   Border Color: #DFDFDF
>   Matte Color: grey74
>   Dispose: Undefined
>   Iterations: 0
>   Compression: Group4
>   Orientation: LeftBottom
>   Make: Wicks and Wilson
>   Model: Wicks and Wilson Rollfilm Scanner
>   Signature:
6c1866aefbf7ea8a979de406e6659a540dc0df115167de95efb251274bdd
1173
>   Software: Wicks and Wilson TIFF VER 1.0
>   Timestamp: 2007:03:05 09:31:06
>   Tainted: False
>   Version: ImageMagick 6.2.4 02/15/07 Q16 http://www.imagemagick.org

> identify: Image 0106.tif: unknown field with tag 32961
(0x80c1) encountered. 
> `TIFFReadDirectory'.
>  conversion?
>   


-- 
Glenn -- http://nevcal.com/
===========================
A protocol is complete when there is nothing left to
remove.
-- Stuart Cheshire, Apple Computer, regarding Zero
Configuration Networking

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Roland Tanner on  wrote...
| Hello,
| 
| As mentioned in quite a few other posts, convert can be
slow in converting 
| images between one format and another, depending on setup.
I am experiencing 
| very slow processing. (Admittedly I'm working on an
underpowered laptop, 
| which does not help).
| 
| Can I get some advice? I have about 1000 tiff images, of
about 500KB each, so 
| not vast as far as tiffs are concerned. They are
monochrome from microfilm. I 
| want to convert them to pngs suitable for website display
- so resize and 
| then convert them. 
| 
| Unfortunately the files were converted on some proprietary
Windows based 
| scanning platform - opening them in the GIMP crashes KDE!
However they are 
| not corrupted. I have put some version info at the end of
this message. Note 
| the 'unknown field' report at the end, which every image
has.
| 
| The advice I need is:
| Will using Q8 rather than Q16 decrease the quality of the
resulting image?
|
Generally no, but it depends on the destination format which
you did not
mention.

| Would resizing first and then converting be better/quicker
than doing in one 
| convert command?
|
Resize during the read process rather than afterward.

| If I want to use Q8, am I going to have to compile it?!
Would I have to 
| unistall Q16 first? I'd rather apt-get, but I can't see it
in my repos.
| 
No. just get the source and build a new one.

See IM Examples, Feedback and Questions
   
http://www.imagemagick.org/Usage/feedback.html#speed

It is very general however.

Also specialized programs may be faster, such as  tif2gif 
from the 
libtiff package, as is is more specific, than a generalised
image
processor.


  Anthony Thyssen ( System Programmer )    <A.Thyssengriffith.edu.au>
 -----------------------------------------------------------
------------------
    Personally, I consider myself perfect and bug free...bug
free... bug
    free...  bug free... bug free... bug free... bug free...
bug free...
        -- Adam Calinsed Cuerden   <acuerdensalsgiver.com>
 -----------------------------------------------------------
------------------
     Anthony's Home is his Castle     http://www.cit.gu.
edu.au/~anthony/
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