Crop with Perspective acting strange

[Rexx Senior Member Find all posts View Profile Close Rexx]

In an upcoming tutorial (look for The X-ray Brush when the Tutorial Publishing System is functional again) I retouched a photo of a church. As a final touch I wanted to correct perspective and used the Crop tool. It worked flawlessly -- I thought. When I compared the images side by side, it turned out the Crop had metamorphosed Legolas into Gimli!

Instead of a tall, stately church I got a squat building of sorts. The height in pixels has been retained, but the ratios between the various levels is weird. It looks like a "funny mirror" in a tivoli.

I have attached an image of a ruler. It seems to me that the change in height ratio follows an unnatural curve. Real life is not as dramatic as this. This looks like an 18mm Wide.

Why? Is there a better way?

[Rexx Senior Member Find all posts View Profile Close Rexx]

Now where is the image? Argh! I forgot to click Upload.

[Rexx Senior Member Find all posts View Profile Close Rexx]

Ok, here's one answer, but it immediately produces two new questions.

If I don't do the perspective change in one fell swoop, but instead in small increments, then height ratio is maintained. Legolas remains Legolas, only with broader shoulders and ... uh ... a swollen head

Q1: Why?
Q2: Will this lead to massive pixel death? My gut feeling is that performing many transformations on a picture will result in loss of detail.

[Ed_L Senior Member Find all posts View Profile Close Ed_L]

Rexx,

I don't have the answers for you. The following is probably *not* your problem, but it's a possibility. When the image looks wierd to you, are you viewing it at 100%? I've seen what appears to be some very strange transformations when viewing at something other than 100%! I have no idea why this is, but if I make a print, it doesn't show up distorted, even though it does on the monitor. Also, if I change the view to 100%, it looks much different (not distorted). This is something that I've only noticed a couple of times, but it came to mind when I read your post.

Now if someone will give the *real* answer, I'd be interested too.

Ed

[sdubose99 Senior Member Find all posts View Profile Close sdubose99]

Rexx, I've tried to understand the issue but I may not be completely "getting it"... to correct perspective, I don't use the crop tool often, I use edit/transform/perspective. That way I can immediately see the results of my adjustments. If you do use the perspective feature of the crop tool, it will maintain the original height -- same as with the edit/transform/perspective feature. It surprises me that you can get the result you want by doing the changes in smaller increments....

One way to do it is to enlarge the height of the canvas prior to doing the correction. Then do edit/transform/perspective to get the vertical walls you are looking for, then increase the height to get the right aspect ratio by edit/transform/distort.

I've looked at the other options for the tools and can't see a way to maintain original aspect ratio "automatically."

sorry I couldn't be more help,
Scott

[Doug Nelson Janitor Find all posts View Profile Close Doug Nelson]

Here's your distorted rule corrected back to "normal" twice, once just using perspective crop on the original image, once using it on the original image with the canvas resized first by 200%