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Question on rotating pix

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Anonymous
January 12, 2005 9:35:02 PM

Archived from groups: rec.photo.digital (More info?)

Every time I rotate a digital photo (doesn't seem to make any
difference what program I use) the image size ends up being about a
third the size of the original. Why is this? Does it mean that I have
lost two-thirds of the quality? Thanks.



_________________________________

"Take a little 5FU, leucovorin and oxaliplatin for thy stomach's sake." -- 1 Timothy 5:23 (adapted)

More about : question rotating pix

Anonymous
January 12, 2005 9:35:03 PM

Archived from groups: rec.photo.digital (More info?)

Are you just rotating it, or saving it as well? If you're saving it, after
you rotate it, and you're working with .jpg format, it will compress
it...and you will sacrifice some quality. See if your editing utility has
the option to reduce compression, when saving files.

Bill Crocker


"Joe-46er" <nobody@nospam.com> wrote in message
news:lbrau01rgj9ojr8i7gkh8ohtp8djri39hb@4ax.com...
> Every time I rotate a digital photo (doesn't seem to make any
> difference what program I use) the image size ends up being about a
> third the size of the original. Why is this? Does it mean that I have
> lost two-thirds of the quality? Thanks.
>
>
>
> _________________________________
>
> "Take a little 5FU, leucovorin and oxaliplatin for thy stomach's sake." --
> 1 Timothy 5:23 (adapted)
Anonymous
January 12, 2005 10:02:56 PM

Archived from groups: rec.photo.digital (More info?)

On Wed, 12 Jan 2005 13:57:50 -0500, "Bill Crocker"
<wcrocker007@comcast.net> wrote:
>
>"Joe-46er" <nobody@nospam.com> wrote in message
>news:lbrau01rgj9ojr8i7gkh8ohtp8djri39hb@4ax.com...
>> Every time I rotate a digital photo (doesn't seem to make any
>> difference what program I use) the image size ends up being about a
>> third the size of the original. Why is this? Does it mean that I have
>> lost two-thirds of the quality? Thanks.
>
>Are you just rotating it, or saving it as well? If you're saving it, after
>you rotate it, and you're working with .jpg format, it will compress
>it...and you will sacrifice some quality. See if your editing utility has
>the option to reduce compression, when saving files.
>
>Bill Crocker

...and does the OP mean file size when he says 'image size' or does he
mean it looks smaller on the screen?

Software exists that can losslessly rotate a JPEG.

If the OP is seeing a smaller file size after rotating, it is safe to
assume that significant quality has been lost.

--
Owamanga!
Related resources
Anonymous
January 12, 2005 10:04:55 PM

Archived from groups: rec.photo.digital (More info?)

Joe-46er wrote:

> Every time I rotate a digital photo (doesn't seem to make any
> difference what program I use) the image size ends up being about
> a third the size of the original. Why is this? Does it mean that I
> have lost two-thirds of the quality?

Some quality is lost, although it's hard to quantify quality. Use a
program for lossless rotation of JPEGs if you want to avoid that.

There's a list at http://sylvana.net/jpegcrop/losslessapps.html
Anonymous
January 13, 2005 2:22:21 AM

Archived from groups: rec.photo.digital (More info?)

Joe-46er <nobody@nospam.com> wrote in
news:lbrau01rgj9ojr8i7gkh8ohtp8djri39hb@4ax.com:

> Every time I rotate a digital photo (doesn't seem to make any
> difference what program I use) the image size ends up being about a
> third the size of the original. Why is this? Does it mean that I have
> lost two-thirds of the quality? Thanks.

Well spotted. The fact that the file size of new image is about 1/3 the
size of the original means that a higher level of compression has been
applied to the image when it is saved to disk. If it was a jpeg file, then
you will have reduced the quality of the image. How visible this loss in
quality will be, only you can judge, as it will depend on such factors as
the print size. Your image editing program should allow you set the
"quality level" of the jpeg compression, so that you can minimise an
attendant quality loss. Alternatively, you could save the image using a
lossless format such as tiff.

IrfanView, a freeware program that is available for download from
www.irfanview.com, will enable you to perform lossless rotations.

--
Witold.
Anonymous
January 13, 2005 5:12:03 AM

Archived from groups: rec.photo.digital (More info?)

"Joe-46er" <nobody@nospam.com> wrote in message
news:lbrau01rgj9ojr8i7gkh8ohtp8djri39hb@4ax.com...
> Every time I rotate a digital photo (doesn't seem to make any
> difference what program I use) the image size ends up being about a
> third the size of the original. Why is this? Does it mean that I have
> lost two-thirds of the quality? Thanks.
>
>
>
> _________________________________
>
> "Take a little 5FU, leucovorin and oxaliplatin for thy stomach's sake." --
> 1 Timothy 5:23 (adapted)

Let me make sure I understand what you are asking. Is the file size smaller?
Or are you just seeing a smaller looking image? I know when I rotate an
image to be vertical, it appears smaller because the software is fitting
the "long side" into the smaller dimension (vertical on most if not all
monitors is smaller than the horizontalmeasurement). This make any sense?
D
Anonymous
January 13, 2005 6:22:22 AM

Archived from groups: rec.photo.digital (More info?)

On Thu, 13 Jan 2005 02:12:03 GMT, "Fitpix"
<David@delawarestudioNOSPAM.com> wrote:

>
>"Joe-46er" <nobody@nospam.com> wrote in message
>news:lbrau01rgj9ojr8i7gkh8ohtp8djri39hb@4ax.com...
>> Every time I rotate a digital photo (doesn't seem to make any
>> difference what program I use) the image size ends up being about a
>> third the size of the original. Why is this? Does it mean that I have
>> lost two-thirds of the quality? Thanks.
>>
>>
>>
>> _________________________________
>>
>> "Take a little 5FU, leucovorin and oxaliplatin for thy stomach's sake." --
>> 1 Timothy 5:23 (adapted)
>
>Let me make sure I understand what you are asking. Is the file size smaller?
>Or are you just seeing a smaller looking image? I know when I rotate an
>image to be vertical, it appears smaller because the software is fitting
>the "long side" into the smaller dimension (vertical on most if not all
>monitors is smaller than the horizontalmeasurement). This make any sense?
>D
>

OK. I'm talking about pix taken w my digital camera. I have it set for
highest quality 5 megapixels. By size I mean the number of bytes. I'm
using XnView for my pic thumb viewer. I often will shoot a pic
portrait (vertical) rather than landscape (horiz). But then the pic is
90 degrees off and I have to turn it to right side up. That's when
there is a loss in pic size (# of bytes) happens. I thought a jpg file
is already compressed as it comes from the digicamera.





_________________________________

"Take a little 5FU, leucovorin and oxaliplatin for thy stomach's sake." -- 1 Timothy 5:23 (adapted)
Anonymous
January 13, 2005 8:31:10 PM

Archived from groups: rec.photo.digital (More info?)

In article <Xns95DD6980C12Bnotherecom@211.29.133.50>,
Witold <not@here.com> wrote:
>Joe-46er <nobody@nospam.com> wrote in
>news:lbrau01rgj9ojr8i7gkh8ohtp8djri39hb@4ax.com:
>
>> Every time I rotate a digital photo (doesn't seem to make any
>> difference what program I use) the image size ends up being about a
>> third the size of the original. Why is this? Does it mean that I have
>> lost two-thirds of the quality? Thanks.
>
>Well spotted. The fact that the file size of new image is about 1/3 the
>size of the original means that a higher level of compression has been
>applied to the image when it is saved to disk. If it was a jpeg file, then
>you will have reduced the quality of the image. How visible this loss in
>quality will be, only you can judge, as it will depend on such factors as
>the print size. Your image editing program should allow you set the
>"quality level" of the jpeg compression, so that you can minimise an
>attendant quality loss. Alternatively, you could save the image using a
>lossless format such as tiff.
>
>IrfanView, a freeware program that is available for download from
>www.irfanview.com, will enable you to perform lossless rotations.
>
>--
>Witold.

From my experience, you have missed the point of the original
poster. My experience is from .jpg images on a Canon 300D shot
as 3 megapixels and standard resolution. The resulting .jpg
files are typically 1.2M-1.3M in size. After moving them to my
workstation I make a pass through them with Irfan 3.95 to use
its 'JPG Lossless Transformations' plugin to rotate the images.
I find the option to 'Auto rotate (according to EXIF orientation)'
works almost all the time. The 'optimize JPG file' option is
enabled as is 'Save with original date/time'. Also the default
'Keep all APP markers' is set.

The resulting .jpg files are always much smaller than the original,
usually less than 700K. The images are the same size, they look
the same to my amateur eye but the filesizes are definitely much
smaller - even if the auto rotate transformation is 'None'.

What does Irfanview's Lossless Rotation with optimizing and
cleaning do to a .jpg image?
Anonymous
January 15, 2005 4:47:17 AM

Archived from groups: rec.photo.digital (More info?)

beu@ist.uwaterloo.ca (Bruce Uttley) wrote in
news:cs6b8u$fub$1@rumours.uwaterloo.ca:

> From my experience, you have missed the point of the original
> poster. My experience is from .jpg images on a Canon 300D shot
> as 3 megapixels and standard resolution. The resulting .jpg
> files are typically 1.2M-1.3M in size. After moving them to my
> workstation I make a pass through them with Irfan 3.95 to use
> its 'JPG Lossless Transformations' plugin to rotate the images.
> I find the option to 'Auto rotate (according to EXIF orientation)'
> works almost all the time.

The "Auto rotate" option simply rotates the image when it is loaded for
display. At that stage the data in the jpeg file should not have been
modified.

> The 'optimize JPG file' option is
> enabled as is 'Save with original date/time'. Also the default
> 'Keep all APP markers' is set.

Once the rotated image is displayed, are you then doing a "Ctrl-S" in
IrfanView to save the file? If so, then this will apply a new round of
jpeg compression to the image, based on what default settings have been
specified for the jpeg "save quality". If you have the save quality set
to 80 or so, you will likely suffer a reduction in file size that you are
experiencing with your files.

> The resulting .jpg files are always much smaller than the original,
> usually less than 700K. The images are the same size, they look
> the same to my amateur eye but the filesizes are definitely much
> smaller - even if the auto rotate transformation is 'None'.

It does seem as if you are resaving the jpeg images at a lower quality
level. Hence the large reduction in file size.

> What does Irfanview's Lossless Rotation with optimizing and
> cleaning do to a .jpg image?

Judging from the very small changes to the file size, it appears to have
no effect on the image data. This would be the preferred way to rotate
your images if you do not want to recompress them.

--
Witold.
Anonymous
January 15, 2005 4:54:55 AM

Archived from groups: rec.photo.digital (More info?)

Joe-46er <nobody@nospam.com> wrote in
news:6vpbu01qdqcu4r3sjoul9r4hlqae0vvpep@4ax.com:

> OK. I'm talking about pix taken w my digital camera. I have it set for
> highest quality 5 megapixels. By size I mean the number of bytes. I'm
> using XnView for my pic thumb viewer. I often will shoot a pic
> portrait (vertical) rather than landscape (horiz). But then the pic is
> 90 degrees off and I have to turn it to right side up. That's when
> there is a loss in pic size (# of bytes) happens. I thought a jpg file
> is already compressed as it comes from the digicamera.

Once the software has rotated the image, it looks like it is being saved
with a higher level of jpeg compression than was used on the original
image. It may be possible to reduce the amount of jpeg compression
(increase the "quality level) to minimise any attendant quality loss
caused by this extra jpeg compression cycle. I'm not familiar with the
features of XnView, but it may allow you to alter the quality level of
the jpegs that it saves. This will minimise any loss of image quality.

As you say, jpegs that come off a digicam are already compressed.
However, different levels of compression can be selected and applied to
the same image. Hence, you can get considerably different files sizes
associated with what is more or less the same image.

--
Witold.
Anonymous
January 16, 2005 7:09:49 PM

Archived from groups: rec.photo.digital (More info?)

In article <Xns95DF8210AA8F9notherecom@211.29.133.50>,
Witold <not@here.com> wrote:
>beu@ist.uwaterloo.ca (Bruce Uttley) wrote in
>news:cs6b8u$fub$1@rumours.uwaterloo.ca:
>
>> From my experience, you have missed the point of the original
>> poster. My experience is from .jpg images on a Canon 300D shot
>> as 3 megapixels and standard resolution. The resulting .jpg
>> files are typically 1.2M-1.3M in size. After moving them to my
>> workstation I make a pass through them with Irfan 3.95 to use
>> its 'JPG Lossless Transformations' plugin to rotate the images.
>> I find the option to 'Auto rotate (according to EXIF orientation)'
>> works almost all the time.
>
>The "Auto rotate" option simply rotates the image when it is loaded for
>display. At that stage the data in the jpeg file should not have been
>modified.
>
> [clipped]

The Irfanview JPG Lossless transformation [version 3.95 and earlier]
overwrites the original image when the transformation is done. The
note at the top of the transformation window says: "Note: This option
will OVERWRITE your original JPG file(s)!" That's what it says it
will do and that's the way it works. No extra 'save' step is needed
where lossy compression enters the picture.

Does Irfanview's JPG Lossless transformation plugin save the file
back after a lossy recompression when "Optimize JPG file" is
selected. Maybe, but I respect Irfanview too much to believe that.

What happens when the Irfanview plugin "Optimizes" the JPG file
on a Lossless Transformation?
Anonymous
January 17, 2005 1:41:20 PM

Archived from groups: rec.photo.digital (More info?)

>>My experience is from .jpg images on a Canon 300D shot
>>as 3 megapixels and standard resolution. The resulting .jpg
>>files are typically 1.2M-1.3M in size. After moving them to my
>>workstation I make a pass through them with Irfan 3.95 to use
>>its 'JPG Lossless Transformations' plugin to rotate the images.
>>I find the option to 'Auto rotate (according to EXIF orientation)'
>>works almost all the time. The 'optimize JPG file' option is
>>enabled as is 'Save with original date/time'. Also the default
>>'Keep all APP markers' is set.
>>
>>The resulting .jpg files are always much smaller than the original,
>>usually less than 700K. The images are the same size, they look
>>the same to my amateur eye but the filesizes are definitely much
>>smaller - even if the auto rotate transformation is 'None'.
>>
>>What does Irfanview's Lossless Rotation with optimizing and
>>cleaning do to a .jpg image?

It is possible to reduce the size of the image file from a camera having
lost nothing. This all arises from the fact that the software (or camera
firmware) producing a jpeg image has an enourmous amount of flexibility as
to how it stores the additional information in the EXIF header. For reasons
of cost, the firmware in the camera typically has to fit into a small amount
of memory so the program has to be kept simple. My Olympus C2100 inserts
huge amounts of meaningless "padding" into every jpeg image it creates.
Why? In order to ensure that the header is always exactly the same size no
matter how much, or how little, extra information is contained in it. It
appears that the firmware designers decided upon a maximum size for the
headers, probably adding a bit for luck, then made sure every header is
exactly that size by inserting padding as necessary. This enables them to
"know" that certain other file components (typically the jpeg data itself)
can be relied upon to be at a fixed file offset, which presumably simplifies
the coding.

I have written my own photo processing application and I _know_ that I can
take a jpeg image from my camera and save it again, keeping all the exif
tags from the original and without changing the jpeg encoded data, and still
reduce the file size. The reduction is not huge, though - of the order of a
few Kb perhaps.

Keith
Anonymous
January 17, 2005 1:41:21 PM

Archived from groups: rec.photo.digital (More info?)

>>What does Irfanview's Lossless Rotation with optimizing and
>>cleaning do to a .jpg image?

If you really want to find out...

1) Take a before and after image and place them (for convenience) in the
same folder

2) Download a (free) copy of my PhotoMan application
(http://homepages.tesco.net/~Keith.Sheppard/photoman/hom...)

3) Open the folder in PhotoMan and for each image in turn right click and
choose "Anatomy" from the pop up menu.

This will produce a report (in HTML format) listing precisely what is in
each file and where. It will give you the sizes of all components
(including the jpeg data) and a complete list of all EXIF tags.

Keith
Anonymous
January 18, 2005 6:34:42 PM

Archived from groups: rec.photo.digital (More info?)

In article <lDMGd.959$0C6.706@newsfe3-win.ntli.net>,
Keith Sheppard <keith.sheppard@tesco.net> wrote:
>>>What does Irfanview's Lossless Rotation with optimizing and
>>>cleaning do to a .jpg image?
>
>If you really want to find out...
>
>1) Take a before and after image and place them (for convenience) in the
>same folder
>
>2) Download a (free) copy of my PhotoMan application
>(http://homepages.tesco.net/~Keith.Sheppard/photoman/hom...)
>
>3) Open the folder in PhotoMan and for each image in turn right click and
>choose "Anatomy" from the pop up menu.
>
>This will produce a report (in HTML format) listing precisely what is in
>each file and where. It will give you the sizes of all components
>(including the jpeg data) and a complete list of all EXIF tags.
>
>Keith

Thank you for the link to your PhotoMan application. I tried it with
a sample 3 megapixel taken on my Canon 300D at its 'standard'
compression and the results were revealing:

Original Camera Image
Total Size: 1,420,450
Various JPG markers: 12,877
Image Size: 861,964
and a WARNING that the file contains extra
data beyond the EOI at 874,841

Irfanview Lossless Rotated Image
Total Size: 863,203
Various JPG markers: 12,653
Image Size: 850,548
and _NO_ WARNING Messages

My conclusion is that for 3 megapixel images at standard compression,
the Canon 300D uses about 60% of the filespace for the image and
40% for 'padding'. I will follow up with the same comparison at
other image sizes and compressions. In the meantime I will continue
the practice of optimizing and cleaning JPG images with Irfanview's
Lossless Transformation plugin.
Anonymous
January 20, 2005 4:34:54 AM

Archived from groups: rec.photo.digital (More info?)

beu@ist.uwaterloo.ca (Bruce Uttley) writes:

>The Irfanview JPG Lossless transformation [version 3.95 and earlier]
>overwrites the original image when the transformation is done. The
>note at the top of the transformation window says: "Note: This option
>will OVERWRITE your original JPG file(s)!" That's what it says it
>will do and that's the way it works. No extra 'save' step is needed
>where lossy compression enters the picture.

>Does Irfanview's JPG Lossless transformation plugin save the file
>back after a lossy recompression when "Optimize JPG file" is
>selected. Maybe, but I respect Irfanview too much to believe that.

>What happens when the Irfanview plugin "Optimizes" the JPG file
>on a Lossless Transformation?

No, it's still lossless. You have to understand that JPEG uses several
different compression steps, some of which are lossy and at least one
that is lossless. Lossless rotation doesn't just move bits around in
the file; it partially uncompresses the image (undoing the lossless
compression step), then rearranges the data, and then re-compresses it
using lossless compression.

The "optimize" box almost certainly controls whether this final lossless
compression step is done fast (normal) or slower but with better
compression (optimized). Either way, you'll get exactly the same image
after full decompression - you're just making a time/size tradeoff.

Dave
Anonymous
January 20, 2005 2:25:49 PM

Archived from groups: rec.photo.digital (More info?)

Bruce Uttley <beu@ist.uwaterloo.ca> wrote:
>
> The Irfanview JPG Lossless transformation [version 3.95 and earlier]

I think you mean "version 3.25 and later" although improvements were made
in versions 3.80 and 3.85.

Thanks, I didn't know about this feature until reading your post!
!