Go Back   Steve's Digicams Forums > Digicam Help > General Discussion

Reply
 
Thread Tools Search this Thread
Old Aug 30, 2009, 1:51 PM   #1
Senior Member
 
Ordo's Avatar
 
Join Date: Jul 2009
Location: BsAs
Posts: 3,452
Default Rotated images problem

Heres a question. When I rotate images the proportion changes and the image gets compressed. Examples:

Original image (just a 4:3 sample pick of my 4:3 LCD)



Rotated 90 right:



You can see the proportion changes.
How can I get a non distorted rotation? Thanks!
Ordo is offline   Reply With Quote
Sponsored Links
Old Aug 30, 2009, 2:17 PM   #2
Administrator
 
Join Date: Jun 2003
Location: Savannah, GA (USA)
Posts: 22,378
Default

The image dimensions are identical. One is just rotated.

I think you're probably just seeing an optical illusion because of the way you captured it (with a touch of perspective distortion because the camera wasn't square to the target, combined with picking up part of the display edge).

When rotated, it probably just seems more distorted than it was to begin with (the perspective distortion is also present in the unrotated image).
JimC is offline   Reply With Quote
Old Aug 30, 2009, 2:57 PM   #3
Senior Member
 
Ordo's Avatar
 
Join Date: Jul 2009
Location: BsAs
Posts: 3,452
Default

May it be my monitor settings Jim?
I'm using a Samsung 19", 4:3, 2000:1 contrast LCD. In it the images have very different proportions. Thanks again.
Ordo is offline   Reply With Quote
Old Aug 30, 2009, 3:19 PM   #4
Administrator
 
Join Date: Jun 2003
Location: Savannah, GA (USA)
Posts: 22,378
Default

I think you're probably just seeing an optical illusion due to the distorted original image (which may have been exaggerated if your monitor has any distortion).

Note how the black edges on both sides of the original are wider at the top and narrower at the bottom. That's perspective distortion caused by the the camera not being square to the monitor when you took the photo (the bottom of the camera was tilted a bit more towards the monitor compared to the top of it when you took the photo, versus being square to it). So, when you rotate it, it's probably causing the illusion that the rotation is distorting it (when it was distorted to begin with).
JimC is offline   Reply With Quote
Old Aug 30, 2009, 3:30 PM   #5
Administrator
 
Join Date: Jun 2003
Location: Savannah, GA (USA)
Posts: 22,378
Default

IOW, you probably took the photo with the camera more towards the bottom of the monitor, tilted up slightly to get the entire display into the frame, causing the problem. You'd need to make sure the camera is centered in the middle of the monitor and square to it (all sides of your camera are at an equal distance to the monitor) if you don't want that kind of distortion.

But, shooting a monitor is probably not a great way to check for a problem anyway (as you can also have problems introduced by the monitor itself). ;-)

I don't see anything that suggests the image is being distorted by your rotation. I think it's just an optical illusion.
JimC is offline   Reply With Quote
Old Aug 30, 2009, 3:40 PM   #6
Senior Member
 
Ordo's Avatar
 
Join Date: Jul 2009
Location: BsAs
Posts: 3,452
Default

I've measured the images on the screen with a rule:

Horizontal- Vertical

1. 23.4 x 18.7 cm. Ratio: 1.26
2. 17.5 x 24,8 cm. Ratio: 1.42

It doesn't seem an optical ilusion. But I will try a new and better image.

Last edited by Ordo; Aug 30, 2009 at 3:45 PM.
Ordo is offline   Reply With Quote
Old Aug 30, 2009, 4:29 PM   #7
Administrator
 
Join Date: Jun 2003
Location: Savannah, GA (USA)
Posts: 22,378
Default

Look at the image properties (just right click on an image and select properties).

One is 640x480 and the rotated version is 480x640. ;-)

In other words, the rotation is not causing the problem you're seeing if they don't measure the same after rotation (as they should given the image dimensions in pixels).

Are you using your monitor's native resolution (probably 1280x1024 with that type of LCD, but I'd check it's specs to make sure)? You may have a graphics setting causing a problem with what you're seeing on screen if you are seeing different measurements with a ruler. Some monitors will still accept something other than their native resolution. But, you can get a distorted image doing it that way if the aspect ratio doesn't match up (not to mention that it can degrade image quality if you don't use the native resolution with an LCD). Or, you have a monitor setting causing it (some monitors allow you to easily adjust the width and height of the displayed image, which could be causing your issue).
JimC is offline   Reply With Quote
Old Aug 30, 2009, 4:54 PM   #8
Administrator
 
Join Date: Jun 2003
Location: Savannah, GA (USA)
Posts: 22,378
Default

IOW, for starters, I'd right click on an open area of your desktop and select Graphics Properties. You should find your display settings there.

If the resolution you have set doesn't match up to your monitor's native resolution (and you should be able to google that if you have your display's model number), change it to match what your display is expecting.

If you don't see an option that matches what your display's native resolution should be, you may need to upgrade your graphics driver. You can get updated drivers for most graphics chipsets from the manufacturer's web sites (for example, amd, nvidia, intel).

If the resolution is already set correctly, then you may need to go into your monitor's settings. Many have a way to adjust the width and height via a screen based menu (and if you have it adjusted incorrectly, with too much or too little space at the top or sides; that may be causing the issue you're seeing).
JimC is offline   Reply With Quote
Old Aug 30, 2009, 5:54 PM   #9
Senior Member
 
Ordo's Avatar
 
Join Date: Jul 2009
Location: BsAs
Posts: 3,452
Default

Exactly Jim. I changed the resolution to the max in this monitor: 1280 x 1024 and now ther're no distortions. My settings were wrong.
Superb. You did it again!
Ordo is offline   Reply With Quote
Old Aug 30, 2009, 6:17 PM   #10
Administrator
 
Join Date: Jun 2003
Location: Savannah, GA (USA)
Posts: 22,378
Default

Great. I couldn't figure out what you were seeing (since the rotated image was identical to the non-rotated image other than being rotated, with the exception of the file size from recompression with the editor you used to rotate it).

But, when you measured it and said it was different, that pointed to a monitor issue. LOL

I do that by accident from time to time (have the wrong resolution set). I test a lot of new Linux distros, and sometimes they don't accurately detect my monitor. It's usually pretty obvious though (text doesn't look like it should, etc.), and so I just change it to what my display needs to work correctly.
JimC is offline   Reply With Quote
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

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 Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 12:30 PM.