It is not really a issue when I design or print something here as I can do my rotation in Indesign with these artifacts not showing, but when I am sending out an image to someone else I hate to send them a crocked image.
Yes I know I should try to load the trany on the drum so I don’t have to rotate later but it is not always possible to get them 100% correct every time.
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You shouldn’t be getting artifacts just from rotating an image. Rotating just reorders the pixels. It doesn’t introduce artifacts, unless you’re then resaving the image as a jpeg.
From what the Op said, it’s not 90 degree rotations that cause the problem.
It may be the texture of the image that casues an interference pattern with the pixels which becomes apparent when rotated a handful of degrees or less.
See this (which is admittedly a worse case scenario):
What I still don’t understand if I rotate an image say a couple of degrees in Indesign I never see this kind of pattern, artifacts, whatever you want to call it. What is Indesign doing different to the file when recalculating for printing?
If Indesign can do this in it’s recalculating for printing why can’t Photoshop do it in it’s normal workflow of rotating an image by a few degrees?
Maybe I am missing something here but where in any printing dialog in PS can you rotate an image.
Beside my printing an image is not the problem. It is when I am send an image out for someone else to use. I don’t really want to send an image that needs to be straitened.
But, I have been thinking of not doing any rotating in PS (when sending out files) and sending a strong statement to the effect about this issue with PS, and why you should not be rotating images with PS.
I don’t consider softening images either buy using a blur filter or buy changing the focus or aperture setting on the drum scanner to be anything desirable, just to keep PS from doing this if the image needs rotated slightly.
Maybe I am missing something here but where in any printing dialog in PS can you rotate an image.
You’re the one who talked about rotating in ID
Beside my printing an image is not the problem.
I know it’s not, but it would be a valid test to see what happens before stating that the problem does not appear when rotating the image in ID
I don’t consider softening images…<snip>…to be anything desirable
The point of my first post was that some softening may be the only option due to th e nature of the image. It is not a function ps PS, but most likely of the image
"Have you tried printing the image rotate in PS to compare it with a print of the image rotated in ID?"
How do you rotate the image when printing in PS.
Yes as I have stated before if you rotate the image in PS and then print it you will certainly see this problem whether you print with PS or Indesign. If you do not rotate in PS but rotate the placed image in Indesign you will not see this problem when printed.
90 degree (180, 270) will never cause artifacts. It is a one to one replacement of pixels.
However when you rotate anything that is not horizontal or perpendicular ps has to calculate pixels with totally new values, based upon value of its nearest surrounding neighbors or some algorythmn (sp?).
In this scenario the higher the quality and rez you start with will give you a better after.
Also, regardless of whether rotations are performed in a RIP at print time or in photoshop (of which I would think does a better job) there stil is that calculation going on.
To really get the picture of this set a few lines of crisp (not anti-aliased) type in grayscale and then rotate 90 degrees and see the result and then rotate to odd angles and zoom in close for a view.
Yes as I have stated before if you rotate the image in PS and then print it you will certainly see this problem whether you print with PS or Indesign. If you do not rotate in PS but rotate the placed image in Indesign you will not see this problem when printed.
So indesign is somehow altering the pixel information when you print from it? It sounds like it might be blurring or interpolating in some way if printing from indesign removes the pattern. Probably not a good thing. I don’t know anything about indesign, but you might want to check those forums to make sure your settings are not altering your images in some unforeseen way.
it’s not that it’s not putting it there, it’s probably removing it. See CN’s post #4. Any digital image that has a pattern of pixels in it, will likely give you some kind of interference pattern when you rotate it at certain angles. This is inescapable. Those pixels have to be interpolated in some way, and this interpolation causes the regular pattern to be reorganized into some other regular pattern. If you had, for example a checkered tablecloth, at a particular size, if you rotated it in photoshop, in the RIP, or with old traditional methods of film and half-tone screening, eventually dots will merge together in ways that result in interference patterns, because you’re taking rows of dots and trying to consolidate them perfectly along an angle, which is somtimes not possible. The pixel will have to fall to one side or the other of that angle. If the rotations you are doing in Indesign and Photoshop are identical, then Indesign is probably doing some kind of interpolation that has smoothed it out more. The solution is pretty simple, just run a despeckle, blur or similar filter before the rotate to lessen the harshness of the resulting pattern. Even adding noise to the affected areas may break up the pattern randomly enough that no interference pattern crops up after a rotate.
Thanks for explanation. That will give me some ideas to try.
I guess I am getting spoiled by digital camera images and think that drum scanned medium format transparencies should be able to achieve the same level of detail, but after having to deal with film grain, etc. like this, it is not going to happen.
I would think that the type of rip would come into play.
A Creo/Scitex rip reinterpolates all rasters, so this pixel-moire might rear its ugly head at the rip if you rotate it in a layout program.
And even if the rip does not reinterpolate rasters there is a chance of this pattern creating a screening moire if conventionally screened.
What I can’t figure out is where the pattern came from in the first place. The title post implies it was scanned from a transparency. Maybe it was a transparency of a printed piece??
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