Imagemaster wrote:
I don't see any distortion:


I did, when I tried it. Jim is absolutely correct.

Just take any photo, and rotate it to the right 2 degrees, save, rotate back 2 degrees, save, then do it again. After the second pass or so, the degradation starts to become quite apparent.

Wow.


Thanks for the heads-up, Jim!

Cableaddict wrote:
... Jim, it's "command - T." (not cntrl)
I guess you're using a mac then?

Cableaddict wrote:
-In CS2, this does open the transform function. However, it only seems to squeeze the image, vertically or horizontally. There's no way to change the horizon orientation.

What you're describing is the same in CS3 & 4 if you grab one of the little "squares". But if you move the cursor completely outside of the image area it changes shape (small angle with arrow heads) ... and you can rotate the whole image. I can't screen-capture the cursor but this is what the image transformation looks like in CS4:

Imagemaster,

Again ... I have no trouble inducing degradation into an image while rotating. Here's the PSD file I used: link. Just arbitrarily rotate it back and forth and you should see what I mean.

However I must say the effect isn't that noticeable and I only mentioned it in passing. Certainly shouldn't put anyone off straightening their photo's out

Well you're right it does degrade. This should be common sense as your pixels are aligned in straight rows - but I think the greater disservice to the photograph is in some cases anyway, leaving it crooked. I guess if the degradation of rotating it bugs someone too much they can just rotate their monitor.

See! Monitors should be round! I knew it...

Bifurcator wrote:
I guess if the degradation of rotating it bugs someone too much they can just rotate their monitor.



-Or you could just drink more beer. Sort of re-align the receptors.

-That's kind of a win-win.

Jim Healey wrote:
Cableaddict wrote:
... Jim, it's "command - T." (not cntrl)
I guess you're using a mac then?



Of COURSE I'm using a Mac!

FTR, I also own three pee-CEES.

-but I hate them.

Cableaddict wrote:
Bifurcator wrote:
I guess if the degradation of rotating it bugs someone too much they can just rotate their monitor.



-Or you could just drink more beer. Sort of re-align the receptors.

-That's kind of a win-win.


hmm ...

+1 on the get it right at time of capture. As far as the angst over Photoshop - I'd say learn your tools. You can use the ruler if you have *anything* you'd like to set at any angle - when you use the angel tool the next time you go to roatte the angle is already there for you. The simplest method for the horizon is to turn on rulers, drag a rule line down to serve as a reference, rotate to taste. In Lightroom when you crop/rotate there are many alignment templates at your disposal. One is a grid. If you have Photoshop CS2 you have the capability to read 5D raw files. Get the latest ACR update from Adobe for CS2 - unless of course we're talking about a bootleg copy.

This subject is really a tempest in a teapot.

Unless you are viewing individual pixels at 100%, the distortion is so minimal as to be irrelevant.

The proper method for rotating images has always been Image > Rotate Canvas, and has been available from the first version of Photoshop, right up to the current version.

I can usually guess how much I have to rotate to get the horizon level, and after rotating I confirm the level by simply putting the cursor on the left side of the horizon and noting where it is on the Ruler scale, then do the same on the right side. Simple as pie.

3 examples of the images rotated, with no discernible distortion:

180 degrees rotation:

I agree - in *principle* there is image degradation but in practice it's not enough to matter.

PS: Nice crispy image of that jay there. What kind is it?

BubbaJon wrote:
I agree - in *principle* there is image degradation but in practice it's not enough to matter.

And any such distortion looks better than an unreal tilted horizon.

PS: Nice crispy image of that jay there. What kind is it?

Thanks, it is a Steller's Jay.

Picasa 3 It's FREE, but dont make mistakes picasa ia a Google stuff, they have plenty of money to spend and the luxury to give away for FREE

Imagemaster wrote:

... Unless you are viewing individual pixels at 100%, the distortion is so minimal as to be irrelevant.

... And any such distortion looks better than an unreal tilted horizon.


I agree. It was just mentioned to the OP in passing and not as a primary response.

Incidentally, He was about methods to straighten the photo, particularly in a visual & incremental manner. Any more takers on that topic?

Imagemaster wrote:
I don't see any distortion:

You're not doing it the right way! Take an image. Rotate it 1 degree CW. Then rotate the result 1 degree CCW. You should get an image equivalent to your original (i.e. not rotated). And there will be a difference.

Looks like you just took one image, made two copies, and rotated each of them individually.

Beowulfenator wrote:
Imagemaster wrote:
I don't see any distortion:

You're not doing it the right way! Take an image. Rotate it 1 degree CW. Then rotate the result 1 degree CCW. You should get an image equivalent to your original (i.e. not rotated). And there will be a difference.

Well, when I have to correct an image due to a non-horizontal horizon, I either rotate CW or CCW, so what do I care if there is distortion when rotated back to the original position, since I would not do that

Looks like you just took one image, made two copies, and rotated each of them individually.

Wrong. In the 3 images below, #1 is the original. #2 is the original rotated 3 degrees CW. #3 is #2 rotated back 3 degrees CCW.

Where is the distortion?

Imagemaster - the last one looks a touch softer than the original (particularly in the words 'original')..

It makes sense, since pixels have to remain squares in a grid, and you aren't rotating the grid, so there is some interpolation in process. It's not a truly invertible process in other words - there is some image degredation. But I don't think it really matters. At least, I've never thought about it until now...

floris wrote:
Imagemaster - the last one looks a touch softer than the original (particularly in the words 'original')..

It makes sense, since pixels have to remain squares in a grid, and you aren't rotating the grid, so there is some interpolation in process. It's not a truly invertible process in other words - there is some image degredation. But I don't think it really matters. At least, I've never thought about it until now...


That may be, but as I said in a previous post: Well, when I have to correct an image due to a non-horizontal horizon, I either rotate CW or CCW, so what do I care if there is distortion when rotated back to the original position, since I would not do that?

Imagemaster wrote:
floris wrote:
Imagemaster - the last one looks a touch softer than the original (particularly in the words 'original')..

It makes sense, since pixels have to remain squares in a grid, and you aren't rotating the grid, so there is some interpolation in process. It's not a truly invertible process in other words - there is some image degredation. But I don't think it really matters. At least, I've never thought about it until now...


That may be, but as I said in a previous post: Well, when I have to correct an image due to a non-horizontal horizon, I either rotate CW or CCW, so what do I care if there is distortion when rotated back to the original position, since I would not do that?

Oh I agree, I was just answering your question


I think in the example you posted earlier with the boxes and a cross in the middle you didn't really see the distortion because the lines were much thicker than in Jim Healey's example..

I guess the take home lesson from this is that it really is worth taking the time to try to level the camera during capture, saves head aches and ever so slight image degredation.. if you mess up, well of course you're better off straightening..

Filter>Distort>Lens correction is also in CS2 and there is a little wheel called angle that will correct the horizon