Questions on film scanning, TIF files

Dear Experts,

Recently, I bought a Nikon coolscan 5000, and
did some scanning of some 35mm transparencies and negs.

I scanned at 16 Bit, used Digital ICE, and saved
in TIF format.

Interestingly, the file sizes were 137 megs big!

I thought that this was odd, because the size of the
images themselves we 3946 x 5959 pixels,
which, if you multiply these, is about 23 megs.

If I scan at 8 bit, it about 1/2 the size.

Why is the TIF file almost 6 times the size of
the image size? What other information
is being stored in TIF?

What are the advantages of TIF format?


Thanks a lot

(Note: I'm really NOT asking how to get smaller file sizes.)

writes:

I thought that this was odd, because the size of the
images themselves we 3946 x 5959 pixels,
which, if you multiply these, is about 23 megs.

This is because it's 16 bits per colour channel, which means every RGB
color pixel is made of 3*16 = 48 bits, which happens to be 6 bytes. If
you scanned monochrome you would be looking at 46 megabyte pictures..

wrote in message
oups.com...
Dear Experts,
....
I scanned at 16 Bit, used Digital ICE, and saved
in TIF format.

Interestingly, the file sizes were 137 megs big!

I thought that this was odd, because the size of the
images themselves we 3946 x 5959 pixels,
which, if you multiply these, is about 23 megs.

In this situation, multiply by a factor of 6 bytes per pixel to convert
megapixels to megabytes: a factor of 3 for each of the red, green, and blue
channels, and a factor of 2 for 16 bit mode.
--

Mike Russell
www.curvemeister.com/forum/

"Mike Russell" -MOVE wrote in message
news:0zPsh.62965

In this situation, multiply by a factor of 6 bytes per pixel to convert
megapixels to megabytes: a factor of 3 for each of the red, green, and
blue channels, and a factor of 2 for 16 bit mode.
--

How many bytes-per-pixel are digital cameras? My own scanner (3600x3600
ppi) produces 16-bit files of about 103 meg--much larger than even the
highest-resolution digital camera.

jeremy wrote:

In this situation, multiply by a factor of 6 bytes per pixel to convert
megapixels to megabytes: a factor of 3 for each of the red, green, and
blue channels, and a factor of 2 for 16 bit mode.
--

How many bytes-per-pixel are digital cameras? My own scanner (3600x3600
ppi) produces 16-bit files of about 103 meg--much larger than even the
highest-resolution digital camera.

digital cameras mostly store the images in jpg files, which apply lossy

compression to the data. Hence the much smaller files. If you use the

so-called RAW mode in a digital camera, then you end up with similar
sized
files to what you get with a scanner.

you can go both ways: save scanner output as jpg, in which case
you see a similar reduction in size.

All sorts of theories and ideas on why it should or should not be done
one
way or the other.

In very general terms: if you want to keep a pristine copy of the
scanner output or
digital camera capture for further post-processing, then use TIFF or
RAW to keep
the image, respectively.

If you don't plan to do any further post-procesing, then jpg is
perfectly fine and
will result in much less disk space being used.

You may also use jpg as the output of any post-processing from TIFF or
RAW.

HTH

[ Excessive crossposting trimmed ]
["Followup-To:" header set to comp.periphs.scanners.]
On 21 Jan 2007 11:43:57 -0800, staggered into the
Black Sun and said:
I scanned at 16 Bit, used Digital ICE, and saved in TIF format. The
[files] were 137 megs! The images themselves were 3946 x 5959 pixels,
which, if you multiply these, is about 23 megs. If I scan at 8 bit,
it about 1/2 the size.

Why is the TIF file almost 6 times the size of the image size?

3946 pixels wide * 5959 pixels high * 6 bytes/pixel (16 bits/channel, R,
G, B channels)= 134M uncompressed. If you save with LZW compression,
you might reduce the size of the images to ~70M, depending on lots of
factors. Whether the software you're using can save things in LZW is
anyone's guess.

What other information is being stored in TIF? What are the
advantages of TIF format?

TIFF files can store a lot of essentially arbitrary data in tags, which
are defined in great detail in the TIFF format specs. Every
TIFF-writing app generally defines Image Length, Image Width, Resolution
(dpi or dpcm), Compression, and Bits/Sample. A bunch of other less
frequently-used tags like Color Profile have been defined by SGI and the
libtiff guys, and there are some apps (like TypeReader 6) that store
app-specific info in TIFF tags that are not officially defined.

For advantages, it's mostly about the tags and platform independence.
Many of the things stored in the tags are important in various types of
image processing, and the structure of TIFF means the tags aren't going
to get lost (as could happen with other ways of encoding that data).
TIFF can also store multiple images in 1 file ("multipage TIFF") which
can be useful in certain circumstances.

libtiff provides a uniform way to get at the raw bitmap(s) and tag info,
no matter what OS or arch you're using, so TIFF is essentially
future-proof. Images stored in formats that aren't Open[0] are going to
be difficult to read when the commercial software provider you're using
decides that Format 0.1 is obsolete and that you have to give them $ for
the privilege of reading your data. This is why a lot of people store
archival copies of images in TIFF. HTH,

[0] JPEG, PNG, and TIFF are open, BMP and GIF are well-understood if not
technically completely open.

--
"I was court-martialled in my absence, and sentenced to death in my
absence, so I said they could shoot me in my absence."
--Brendan F. Behan
Matt G|There is no Darkness in Eternity/But only Light too dim for us to see

On Sun, 21 Jan 2007 11:43:57 -0800, photoguy_222 wrote:

Dear Experts,

Recently, I bought a Nikon coolscan 5000, and
did some scanning of some 35mm transparencies and negs.

I scanned at 16 Bit, used Digital ICE, and saved
in TIF format.

Interestingly, the file sizes were 137 megs big!

I thought that this was odd, because the size of the
images themselves we 3946 x 5959 pixels,
which, if you multiply these, is about 23 megs.

If I scan at 8 bit, it about 1/2 the size.

Why is the TIF file almost 6 times the size of
the image size? What other information
is being stored in TIF?

Mainly because you specified a 16 bit tif. 16 bits is two bytes of
information for each channel R, G, B: 2 times three is six - ergo size is
six times the total number of pixels.


What are the advantages of TIF format?

No loss of information.



Thanks a lot

(Note: I'm really NOT asking how to get smaller file sizes.)

On Sun, 21 Jan 2007 21:10:10 +0000, jeremy wrote:

"Mike Russell" -MOVE wrote in message
news:0zPsh.62965

In this situation, multiply by a factor of 6 bytes per pixel to convert
megapixels to megabytes: a factor of 3 for each of the red, green, and
blue channels, and a factor of 2 for 16 bit mode.
--

How many bytes-per-pixel are digital cameras? My own scanner (3600x3600
ppi) produces 16-bit files of about 103 meg--much larger than even the
highest-resolution digital camera.

My calculations show 3600x3600x6 = 77mb. Assuming 16 bits for each color
channel. I can't see how you get 103mb, unless you're using a format which
might include a 16 bit alpha channel, as well.

ray wrote:
On Sun, 21 Jan 2007 21:10:10 +0000, jeremy wrote:

"Mike Russell" -MOVE wrote in message
news:0zPsh.62965

In this situation, multiply by a factor of 6 bytes per pixel to convert
megapixels to megabytes: a factor of 3 for each of the red, green, and
blue channels, and a factor of 2 for 16 bit mode.
--

How many bytes-per-pixel are digital cameras? My own scanner (3600x3600
ppi) produces 16-bit files of about 103 meg--much larger than even the
highest-resolution digital camera.

My calculations show 3600x3600x6 = 77mb. Assuming 16 bits for each color
channel. I can't see how you get 103mb, unless you're using a format which
might include a 16 bit alpha channel, as well.

He said 3600 ppi, not 3600 pixels, I come out with 104,136,400 for a
full frame scan at 3600 ppi
and 16 bits / color.

Of course he better then the hightest-resolution digital camera is a
bit off.

Scott

On Sun, 21 Jan 2007 17:34:43 -0800, Scott W wrote:


ray wrote:
On Sun, 21 Jan 2007 21:10:10 +0000, jeremy wrote:

"Mike Russell" -MOVE wrote in message
news:0zPsh.62965

In this situation, multiply by a factor of 6 bytes per pixel to convert
megapixels to megabytes: a factor of 3 for each of the red, green, and
blue channels, and a factor of 2 for 16 bit mode.
--

How many bytes-per-pixel are digital cameras? My own scanner (3600x3600
ppi) produces 16-bit files of about 103 meg--much larger than even the
highest-resolution digital camera.

My calculations show 3600x3600x6 = 77mb. Assuming 16 bits for each color
channel. I can't see how you get 103mb, unless you're using a format which
might include a 16 bit alpha channel, as well.

He said 3600 ppi, not 3600 pixels, I come out with 104,136,400 for a
full frame scan at 3600 ppi
and 16 bits / color.

Of course he better then the hightest-resolution digital camera is a
bit off.

Scott

You're right, of course. In which case the size of the file is related to
the size of the image.