Question regarding rotation of image with transparent background

[RingRoller]

I want to overlap two images and place an image with a transparent background on top

and rotate only the image on the top.

The transparent background of the upper image should be invisible so that the lower image can be seen,

and it should be able to rotate around the desired point depending on the user's input angle(encoder value).

I have attached the explanatory material and two necessary images (background, rotating object),

so I would appreciate advice and examples from experts.

I use LabVIEW 2019 version.

Thank you.

[Bob_Schor]

Which Image is which?  What relationship does the PowerPoint "image" have with your task?  Have you successfully taken the "transparent background "rotatable" image" and made another "rotated" image (say at 30 deg anti-clockwise, which, to me, is a "positive rotation") and (a) looked at it and seen "what you expect" and (b) put it "on top of" your "Base" image (and see if it is what you expect)?

Why don't you post a small LabVIEW program that does each of these tasks?  Make it a Demo LabVIEW Project, include the "Base" and "Transparent" images in the Project (so we can try it, too) and we'll be better able to understand the "problem" and help with a "solution".  You may want to right-click the Demo Project folder and "Send to:" "Compressed (ziipped) folder" to reduced the Project to a single .zip file.

Bob Schor

[aeastet]

How far do you need it to rotate? I have done this int he past with a picture ring. It is a little more complicated that it should be and it will take a little time to make it look good.

[altenbach]

Well, a picture is just a 2D array and you could start here and conditionally only replace values that are not e.g. black.

(Initialize a shift register with the 2D array of the background picture, do a conditional replacement with the rotated value at each pixel that needs it.. Should be easy to implement)