I need to rotate an entire image with the whole image remaining and no change in the image, when the rotate tool is used to rotate an image with no interpolation the image is modified a little bit. I have a mathmap script that does some of what I need but doesn't keep the entire image in its original state. this is it:

filter slide (image in)

if y>=x then


in(xy:[x,y-x-1])


end


end

Did you try Geometry rotate in MathMap? The radian of 45 degrees would = .785 (in case you didn't understand the angle rotation in radians)

I have just tried it and i'm not sure how to rotate exactly 45 degrees with keeping the original image

Maybe I am not understanding your request: Do you want the original image to not lose quality? Or to leave an unaltered image at its current state while rotating a copy?

I want to rotate an image 45 degrees without the image being altered at all, apart from the whole image being rotated 45 degrees. I would use the rotate tool but it alters the image a bit.

What interpolation method are you using with the rotate tool? Rotating the image 45° will degrade it since there is not a one-to-one pixel correspondance between the two, but some interpolation methods are better than others.

I was using no interpolation and the lines in the image below became 3 pixels wide at random times (so it altered the image)

Sounds like you are trying to keep the bitmap as an object container and then rotating that container. The best way to do this based on my understanding of what you want is to use a vector editor like Inkscape.

the mathmap script I provided above I think kept the original image it just cut part of it out, can somebody change the script to where it doesn't cut any part out?

ok I have the correct image now on the screen in inkscape what do I do now, like how do I save it?

File>Export and choose filename.png.

If you take your original image, go to Image > Canvas Size > 200% and click "Center", and then ok. Then do a "layer to image size". Now use your mathmap to rotate it. Now you have the image rotated, without cutting anything away.

I just tried your script and it skews the image instead of rotating it, so my idea won't work. Let me play some more and see what I can come up with.

Remember to click the Export button on the dialog after you select a location and name to save it as.

If you enlarge the canvas, as I said above, and then do Filters > Map > Map to Object, set "Plane", transparent object on, and then on the orientation tab set Rotation x=45. See if this does it well enough.

The bottom line is, you will change the image! you have to, as you are converting from a square pixel grid to a 45deg rotated diamond grid.

Each "pixel" that used to be 1x1 is now spread across a 1.41 by 1.41 px diamond, so will have to either be interpolated (blurred) or nearest neighbor selected (interpolation none).

-Rob A>

The image will definitely be changed, as there is no way to rotate 45 degrees and not have a change. The trick is to find what will show the change the least.

the only rotation that doesn't degrade bitmap images is of 90° ,and multiplies as 180° or 270° ,because are from a square grid to a similar square grid

anyway if the image is at high resolution a single rotation should not cause too visible degradation.

I suppose you get better result with mathmap because of the mathmap supersampling option, not sure if gimp may use something similar when rotating

BTW
you are right should be really easy modify the MM script to avoid cropping but i don't know the MM language, you may try to ask on the flickr and google MM group (no much traffic there but is worth to try, for who know the syntax should be a quick thing , just multiply W and H of the new image of 1.42)

hy thinking better you may do: before run MM do Image/canvas size and increase of x1.5 (easily then 1.42)then "Layer to image size"

and then you may use MM without risk to crop the layer

OK - Looking at your example,I think you want this:



-Rob A>