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Rotate a photo without changing aspect ratio

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Thread started 26 May 2012 (Saturday) 08:26   
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jim4065
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Hope the term in the title isn't wrong. When I use GIMP or Irfanview or Windows Picture Viewer to rotate a picture that's "lying on it's side", it cuts down the height in relation to the width. I know this sounds extremely basic, but how do I rotate without changing the height to width relationship? ???

Post #1, May 26, 2012 08:26:12




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scotthidley
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Rotating a picture file does not crop or resize it. Check the image properties first, then rotate, and you will see the width and height features have swapped values with each other.

Post #2, May 26, 2012 08:44:31




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Lowner
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In Windows live photo gallery at the bottom right are icons for rotating right or left. neither changes the original image in any way other than the rotation.

The same can be done in something like Photoshop and then resave in the new orientation.

Post #3, May 26, 2012 08:47:47


Richard

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sandpiper
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jim4065 wrote in post #14487124external link
Hope the term in the title isn't wrong. When I use GIMP or Irfanview or Windows Picture Viewer to rotate a picture that's "lying on it's side", it cuts down the height in relation to the width. I know this sounds extremely basic, but how do I rotate without changing the height to width relationship? ???

Shoot square photographs. :D

The only other ways to keep an image that is a ratio of 3 wide to 2 tall at 3 wide to 2 tall, after rotating it 90 degrees, is to either crop out a huge amount of the image from the top and/or bottom, add a lot of empty canvas to either/both side(s) or stretch the image to fit the new dimensions, which would be massively distorted.

Your software isn't altering the image it is simply turning it which, as Scot points out, swaps over the height and width values. You cannae fight the laws of physics.

Post #4, May 26, 2012 08:56:02




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Bad ­ Habit
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It is probably just changing the screen size of the image so it will fit on the screen. H/W ratio would stay the same but it appears to be smaller as now the long dimension has to be shorter so it fits (unless you turn your screen to portrait orientation

Post #5, May 26, 2012 09:02:19


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tonylong
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Like Scott says -- in the Windows Picture viewer, right-click on the image and check the Properties. It should give the pixel dimensions. Then, rotate it and check the Properties again. The dimensions should be the same. If they aren't something is amiss and you can update us!

Post #6, May 26, 2012 10:14:19


Tony
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jim4065
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You're right. The pixel dimensions are the same, just swapped, So it must be this new monitor. I had a basically square monitor which I just "upgraded" to a wide-screen monitor. So if I want to look at a "true" picture, I have to be looking at a square monitor? It begs the question - how do I look at an "unstretched" picture in a "stretched" monitor? (And also - why do people buy these things?)

I just had GIMP open a new image and set the size at 400 x 400 pixels, A ruler held against the screen revealed a size of maybe 6" wide by 4" tall (hard to see the ruler against the screen). So does that mean that I should set the screen resolution to where height and width are the same? Doesn't that mean that I'm throwing away a lot of real estate? The "lit-up" part of the screen is about 19" wide by 10 3/4" high. How do I get to where I see a square picture again - if you catch my drift?

Post #7, May 26, 2012 11:32:09 as a reply to tonylong's post 1 hour earlier.




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scotthidley
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If you had a square picture before with images that do not have the same width and height values, then your resolution settings were wrong. You should set the resolution to what best suits the monitor. If you like square pictures afterwards, you should crop them to your taste, but you will be losing picture content. If cropping the pictures, I would suggest saving them under a new name in case you want to go back to the original some day.

Post #8, May 26, 2012 11:52:57




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jim4065
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I scanned this with an MG5320 printer, The sideways one is "as scanned" whereas the "upright" one was rotated 90 degrees in GIMP. I did have to back off the resolution to 1024 on the long side.

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Post #9, May 26, 2012 12:15:03




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tonylong
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My screen resolution is 1920x1080 pixels. So, if I'm viewing an image that "fits" those dimensions, if it is "horizontally" oriented, I can see the image at its "native" resolution. For example, if I size an image for displaying outside of POTN, I can size it to 1080 pixels at the highest, meaning that a horizontal image could be 1620 pixels wide, 1080 pixels tall. So, if my software is designed to display the image at "full size", that's what I would see on my screen.

But if I rotate it, of course, the viewing software would either show me just 1080 pixels of the image in height (if viewing at "full size") or it would "fit to screen", meaning to shrink the 1620 pixels down to 1080 for viewing.

Typically, viewing software gives you the option.

Post #10, May 26, 2012 12:16:33


Tony
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Tony Long Photos on PBaseexternal link
Wildlife project pics hereexternal link, Biking Photog shoots hereexternal link, "Suburbia" project hereexternal link! Mount St. Helens, Mount Hood pics hereexternal link

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jim4065
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AH-HA! I looked at my nVidia screen resolution - it was set at a low number. I moved it to 1920 x 1080 (native) and suddenly it all works. Now - when I look at the two pictures posted above, they look exactly the same. Before, the bottom one was stretched so that the tub appeared MUCH longer. Since ya'll have been looking at an image on a correctly set monitor there was no apparent difference to you. Free at last, Free at last - Thank God I'm Free at Last! (With apologies to MLK, Jr.)

Post #11, May 26, 2012 13:34:57




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tonylong
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jim4065 wrote in post #14488081external link
AH-HA! I looked at my nVidia screen resolution - it was set at a low number. I moved it to 1920 x 1080 (native) and suddenly it all works. Now - when I look at the two pictures posted above, they look exactly the same. Before, the bottom one was stretched so that the tub appeared MUCH longer. Since ya'll have been looking at an image on a correctly set monitor there was no apparent difference to you. Free at last, Free at last - Thank God I'm Free at Last! (With apologies to MLK, Jr.)

Well, good for you!

It's always nice when we can wade through confusing problems and "get it right"!

Post #12, May 26, 2012 14:12:15


Tony
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Tony Long Photos on PBaseexternal link
Wildlife project pics hereexternal link, Biking Photog shoots hereexternal link, "Suburbia" project hereexternal link! Mount St. Helens, Mount Hood pics hereexternal link

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