Velocity Reviews - Computer Hardware Reviews

Velocity Reviews > Newsgroups > Computing > Digital Photography > Is it true that image is degrade after rotation?

Reply
Thread Tools

Is it true that image is degrade after rotation?

 
 
Editor www.nutritionsoftware.org
Guest
Posts: n/a
 
      12-01-2003
If so why?
I remember seeing this warning when rotating a horizontal image to vertical
in Windows viewer.
Thanks for any explanation.

--
Editor, Internet's Convenient and Unbiased Directory of Nutrition Software
http://nutritionsoftware.org



 
Reply With Quote
 
 
 
 
Andrew McDonald
Guest
Posts: n/a
 
      12-01-2003
Editor www.nutritionsoftware.org wrote:
> If so why?
> I remember seeing this warning when rotating a horizontal image to vertical
> in Windows viewer.


It depends on the application doing the rotation. The "normal" reason
why there might be degradation is that when you rotate a .JPG image it
has to be resaved which caused the compression to be done again,
creating more compression artifacts.

However, there are programs that can rotate the JPG image without
recompressing it and those programs cause absolutely no deradation of
the image. I use PIE (Picture Information Extractor) myself. I allows
for lossless JPG rotation.

Other programs will do it as well, I think the freeware IrfanView does it.

 
Reply With Quote
 
 
 
 
Mxsmanic
Guest
Posts: n/a
 
      12-01-2003
"Editor www.nutritionsoftware.org" <nseditor2002 http://www.velocityreviews.com/forums/(E-Mail Removed)>
writes:

> If so why?


The image is not degraded if it is rotated a multiple of 90 degrees.
Otherwise degradation is possible and probable (but not certain).

The problem is that there are rounding and other errors in interpolating
the old pixels to the new pixels that almost inevitably sacrifice image
information during the rotation. There are a few specific types of
rotation that fully avoid this (rotating in multiples of 90 degrees is
one example), but in most cases there is some loss, however small.

--
Transpose hotmail and mxsmanic in my e-mail address to reach me directly.
 
Reply With Quote
 
Mark Johnson
Guest
Posts: n/a
 
      12-01-2003
"Editor www.nutritionsoftware.org" <nseditor2002 (E-Mail Removed)>
wrote:

>If so why?
>I remember seeing this warning when rotating a horizontal image to vertical
>in Windows viewer.
>Thanks for any explanation.


As someone else just mentioned, I think it's just the jpg format
that's at issue. Even a 100% 'uncompressed' jpg still attempts some
compression, and loss of info. And that can accumulate if you use a
lot of filtering and sharpening and so on, to where the photo might be
a lesser quality for repeatedly loading and saving in jpg. So if you
start with a jpg, always save it in uncompressed png, for example,
before doing anything else. Only go back to jpg for the final print -
say if the photo shop only takes jpg.
 
Reply With Quote
 
IMKen
Guest
Posts: n/a
 
      12-01-2003
I use Photoshop 7 or Nikon View 6 and both alter the image making it
unsuitable. Both alter the photo so that people or other objects become
noticeably thinner when rotated from horizontal to vertical. If there is
a solution please pass it along. I hate making my chubby friends look lean
and mean.

Ken



"Mark Johnson" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> "Editor www.nutritionsoftware.org" <nseditor2002 (E-Mail Removed)>
> wrote:
>
> >If so why?
> >I remember seeing this warning when rotating a horizontal image to

vertical
> >in Windows viewer.
> >Thanks for any explanation.

>
> As someone else just mentioned, I think it's just the jpg format
> that's at issue. Even a 100% 'uncompressed' jpg still attempts some
> compression, and loss of info. And that can accumulate if you use a
> lot of filtering and sharpening and so on, to where the photo might be
> a lesser quality for repeatedly loading and saving in jpg. So if you
> start with a jpg, always save it in uncompressed png, for example,
> before doing anything else. Only go back to jpg for the final print -
> say if the photo shop only takes jpg.



 
Reply With Quote
 
Michael A. Covington
Guest
Posts: n/a
 
      12-01-2003

"IMKen" <(E-Mail Removed)> wrote in message
news:AQAyb.60549$(E-Mail Removed)...
> I use Photoshop 7 or Nikon View 6 and both alter the image making it
> unsuitable. Both alter the photo so that people or other objects become
> noticeably thinner when rotated from horizontal to vertical. If there

is
> a solution please pass it along. I hate making my chubby friends look

lean
> and mean.


I do not even know how such a problem could arise. Rotating an image 90
degrees (an exact right angle) is merely a matter of swapping the vertical
and horizontal coordinates.

QUESTION: Is there something wrong with your monitor? You may be using a
video mode that doesn't suit it. Use Photoshop to create something that is
perfectly square (e.g., a canvas 300 x 300 pixels) and measure it on your
screen. Is it rectangular?

If so, the problem is with screen adjustments.


 
Reply With Quote
 
Don Stauffer
Guest
Posts: n/a
 
      12-01-2003
Only when rotation is 90 degrees is compression the only source of
degradation. If rotation is anything other than 90 or 180, then
resampling MUST be done, and resampling itself can cause degradation
regardless of compression or what format the file is stored in.

This degradation is likely to be minor, so do not hesitate to rotate if
the image really calls for it, but be aware that shooting so that
rotation is not required is best.

Mark Johnson wrote:
>
> "Editor www.nutritionsoftware.org" <nseditor2002 (E-Mail Removed)>
> wrote:
>
> >If so why?
> >I remember seeing this warning when rotating a horizontal image to vertical
> >in Windows viewer.
> >Thanks for any explanation.

>
> As someone else just mentioned, I think it's just the jpg format
> that's at issue. Even a 100% 'uncompressed' jpg still attempts some
> compression, and loss of info. And that can accumulate if you use a
> lot of filtering and sharpening and so on, to where the photo might be
> a lesser quality for repeatedly loading and saving in jpg. So if you
> start with a jpg, always save it in uncompressed png, for example,
> before doing anything else. Only go back to jpg for the final print -
> say if the photo shop only takes jpg.


--
Don Stauffer in Minnesota
(E-Mail Removed)
webpage- http://www.usfamily.net/web/stauffer
 
Reply With Quote
 
Ray Murphy
Guest
Posts: n/a
 
      12-01-2003

----------
In article <(E-Mail Removed)>, Mark Johnson
<(E-Mail Removed)> wrote:


>"Editor www.nutritionsoftware.org" <nseditor2002 (E-Mail Removed)>
>wrote:
>
>>If so why?
>>I remember seeing this warning when rotating a horizontal image to vertical
>>in Windows viewer.
>>Thanks for any explanation.

>
>As someone else just mentioned, I think it's just the jpg format
>that's at issue.


RM: There are other "lossy" formats, but JPEG is the main one to be
concerned about.

>Even a 100% 'uncompressed' jpg still attempts some
>compression, and loss of info. And that can accumulate if you use a
>lot of filtering and sharpening and so on, to where the photo might be
>a lesser quality for repeatedly loading and saving in jpg.


RM: I have experimented with this and found that if the highest
quality is used the image is not degraded further.

> So if you
>start with a jpg, always save it in uncompressed png, for example,
>before doing anything else. Only go back to jpg for the final print -
>say if the photo shop only takes jpg.


RM: That's a good idea if you don't want anything to go wrong.

Here's how to avoid loss of quality when working with JPEGS:

PHOTOSHOP
* Do not "SAVE" the job, but "SAVE AS" (with the same name). This will
automatically throw up the page in Photoshop where you can control the
compression.
When you get there, place the slider at the highest quality and the
JPEG quality will remain identical.

PAINTSHOP PRO
If you are using Paintshop Pro you need to select "Options" after
selecting "Save" or "Save As" and this will allow saving at the best
compression without any degradation of the image.

This can be proven by doing it and measuring the precise colour of
pixels from an original and a "Saved As" copy in Photoshop or the
"Saved" copy in Paintshop Pro.

Both Photoshop and Paintshop Pro have default saving modes which are
of fairly low quality but as indicated above, they can be altered.

Ray





 
Reply With Quote
 
zbzbzb
Guest
Posts: n/a
 
      12-01-2003
>RM: Yes, if you rotate any image at any angle other than 90, 180 or
>270 degrees it is degraded because it has to be re-constructed.



Thing is though if you start off with a very large file to begin with it is
hard if not impossible to see any degradation. In my case rotating 60 meg files
from 4000dpi negative scans. I can't see any obvious effect on them after
rotating. If I work with a much smaller file then the effects are very
noticeable.




This
>can be very easily checked by making a solid box (without any fuzzy
>edges) and then rotating it.
>The fuzzy edges in the original can be removed by the eraser (as if
>that was not obvious to everyone).
>
>Incidentally, talking about rotating images. We cannot rotate B+W
>bitmap images in the Bitmap mode. We have to convert any such images
>to grayscale first and then rotate and go back to bitmap.
>
>Ray
>





 
Reply With Quote
 
Ray Murphy
Guest
Posts: n/a
 
      12-01-2003

----------
In article <UAwyb.28348$(E-Mail Removed) >, "Editor
www.nutritionsoftware.org" <nseditor2002 (E-Mail Removed)> wrote:

[Is it true that image is degrade after rotation?]

>If so why?
>I remember seeing this warning when rotating a horizontal image to vertical
>in Windows viewer.
>Thanks for any explanation.
>
>--
>Editor, Internet's Convenient and Unbiased Directory of Nutrition Software


RM: Yes, if you rotate any image at any angle other than 90, 180 or
270 degrees it is degraded because it has to be re-constructed. This
can be very easily checked by making a solid box (without any fuzzy
edges) and then rotating it.
The fuzzy edges in the original can be removed by the eraser (as if
that was not obvious to everyone).

Incidentally, talking about rotating images. We cannot rotate B+W
bitmap images in the Bitmap mode. We have to convert any such images
to grayscale first and then rotate and go back to bitmap.

Ray
 
Reply With Quote
 
 
 
Reply

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
problem in running a basic code in python 3.3.0 that includes HTML file Satabdi Mukherjee Python 1 04-04-2013 07:48 PM
[False,True] and [True,True] --> [True, True]????? bdb112 Python 45 04-29-2009 02:35 AM
Coolpix 4500 - starting to degrade in quality after heavy use niemeyer Digital Photography 12 01-24-2006 08:32 AM
How do I degrade bandwidth or pingflood IP/LINK? KidVoip VOIP 0 01-11-2006 08:01 PM
Does software used to print enhance or degrade photo? Ray Hurst Digital Photography 8 11-16-2003 11:51 PM



Advertisments