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From: Chris Cox <ccox@adobe.com>
To: Keshab Neupane <neupane.keshab@yahoo.com>, TIFF <tiff@lists.maptools.org>
Date: Tue, 16 Jun 2009 14:56:20 -0700
Thread-Topic: [Tiff] Tiff 16 bit and 32 bit images + some more questions
	about tiff file format
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Subject: Re: [Tiff] Tiff 16 bit and 32 bit images + some more questions
 about tiff file format
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It doesn't say bilevel, it says min-is-black:  aka grayscale.
See the TIFF6 spec., section 3.

Zero is black, higher values are brighter.  For the integer forms, that mea=
ns that the full scale value is white.  For floating point the white point =
is undefined, but is typically 1.0.

Chris


On 6/16/09 2:50 PM, "Keshab Neupane" <neupane.keshab@yahoo.com> wrote:

Hi,

Bilevel images only need 1 bit per pixel.
Larger values make no sense for bilevel images - I think you have made a mi=
stake in parsing those files.

Here, what I get from tiffinfo...please note that these are not normal tiff=
 images but geotiff images....

TIFF Directory at offset 0x8 (8)
  Image Width: 2160 Image Length: 900
 Bits/Sample: 16
 Sample Format: unsigned integer
  Compression Scheme: None
  Photometric Interpretation: min-is-black
 Samples/Pixel: 1
  Rows/Strip: 1
  Planar Configuration: single image plane
=3D=3D> bps =3D 16, but bi-level images ??

 TIFF Directory at offset 0x8 (8)
  Image Width: 2160 Image Length: 900
 Bits/Sample: 16
  Sample Format: signed integer
 Compression Scheme: None
  Photometric Interpretation: min-is-black
 Samples/Pixel: 1
  Rows/Strip: 1
  Planar Configuration: single image plane
=3D=3D> bps =3D 16, but signed integer sample format, and bi-level images ?=
?

TIFF Directory at offset 0xac074 (704628) (why the offset isn't at 8)
 Image Width: 719 Image Length: 245
 Bits/Sample: 32
  Sample Format: IEEE floating point
 Compression Scheme: None
 Photometric Interpretation: min-is-black
 Samples/Pixel: 1
  Rows/Strip: 2
  Planar Configuration: single image plane
=3D=3D> bps =3D 32, but bi-level-images and floating point sample format

This is what made me confused. Thanks to Chris and Bob for your support.
I just started playing with tiff files, definitely a long way to go. :)

Cheers,
Keshab



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Content-Transfer-Encoding: quoted-printable

<HTML>
<HEAD>
<TITLE>Re: [Tiff] Tiff 16 bit and 32 bit images + some more questions about=
 tiff file format</TITLE>
</HEAD>
<BODY>
<FONT FACE=3D"Myriad Pro"><SPAN STYLE=3D'font-size:10pt'>It doesn&#8217;t s=
ay bilevel, it says min-is-black: &nbsp;aka grayscale.<BR>
See the TIFF6 spec., section 3.<BR>
<BR>
Zero is black, higher values are brighter. &nbsp;For the integer forms, tha=
t means that the full scale value is white. &nbsp;For floating point the wh=
ite point is undefined, but is typically 1.0.<BR>
<BR>
Chris<BR>
<BR>
<BR>
On 6/16/09 2:50 PM, &quot;Keshab Neupane&quot; &lt;<a href=3D"neupane.kesha=
b@yahoo.com">neupane.keshab@yahoo.com</a>&gt; wrote:<BR>
<BR>
</SPAN></FONT><BLOCKQUOTE><FONT FACE=3D"Myriad Pro"><SPAN STYLE=3D'font-siz=
e:10pt'>Hi,<BR>
<BR>
</SPAN></FONT><BLOCKQUOTE><FONT FACE=3D"Myriad Pro"><SPAN STYLE=3D'font-siz=
e:10pt'>Bilevel images only need 1 bit per pixel.<BR>
Larger values make no sense for bilevel images &#8211; I think you have mad=
e a mistake in parsing those files.<BR>
</SPAN></FONT></BLOCKQUOTE><FONT FACE=3D"Myriad Pro"><SPAN STYLE=3D'font-si=
ze:10pt'> <BR>
Here, what I get from tiffinfo...please note that these are not normal tiff=
 images but geotiff images....<BR>
<BR>
TIFF Directory at offset 0x8 (8)<BR>
&nbsp;&nbsp;Image Width: 2160 Image Length: 900<BR>
<B> &nbsp;Bits/Sample: 16<BR>
</B> &nbsp;Sample Format: unsigned integer<BR>
&nbsp;&nbsp;Compression Scheme: None<BR>
&nbsp;<B> Photometric Interpretation: min-is-black<BR>
</B> &nbsp;Samples/Pixel: 1<BR>
&nbsp;&nbsp;Rows/Strip: 1<BR>
&nbsp;&nbsp;Planar Configuration: single image plane <BR>
=3D=3D&gt; bps =3D 16, but bi-level images ??<BR>
<BR>
&nbsp;TIFF Directory at offset 0x8 (8)<BR>
&nbsp;&nbsp;Image Width: 2160 Image Length: 900<BR>
<B> &nbsp;Bits/Sample: 16<BR>
&nbsp;&nbsp;Sample Format: signed integer<BR>
</B> &nbsp;Compression Scheme: None<BR>
&nbsp;<B> Photometric Interpretation: min-is-black<BR>
</B> &nbsp;Samples/Pixel: 1<BR>
&nbsp;&nbsp;Rows/Strip: 1<BR>
&nbsp;&nbsp;Planar Configuration: single image plane <BR>
=3D=3D&gt; bps =3D 16, but signed integer sample format, and bi-level image=
s ??<BR>
<BR>
TIFF Directory at offset 0xac074 (704628) (why the offset isn't at 8)<BR>
&nbsp;Image Width: 719 Image Length: 245<BR>
<B> &nbsp;Bits/Sample: 32<BR>
&nbsp;&nbsp;Sample Format: IEEE floating point<BR>
</B> &nbsp;Compression Scheme: None<BR>
<B> &nbsp;Photometric Interpretation: min-is-black<BR>
</B> &nbsp;Samples/Pixel: 1<BR>
&nbsp;&nbsp;Rows/Strip: 2<BR>
&nbsp;&nbsp;Planar Configuration: single image plane <BR>
=3D=3D&gt; bps =3D 32, but bi-level-images and floating point sample format=
<BR>
<BR>
This is what made me confused. Thanks to Chris and Bob for your support.<BR=
>
I just started playing with tiff files, definitely a long way to go. :)<BR>
<BR>
Cheers,<BR>
Keshab<BR>
<BR>
&nbsp;<BR>
</SPAN></FONT></BLOCKQUOTE>
</BODY>
</HTML>


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