It’s fairly easy to blend two images in GIMP. All you have to do is: Open the two Images in GIMP. Blend the images using layer opacity/blend mode/layer mask. Export the resultant image as JPEG/PNG.
To make an image transparent in PowerPoint, you have to change the opacity of the image – and you can do it for the whole image or a part. Change the opacity of an image in PowerPoint When it comes ...