1920x1920 pixels seen as in a 'canvas image' This seems to be the common desired dimensions for many shows now. I used Adobe Photoshop. I started with the image saved as a tif image. Important to do this as it preserves the image the best while it is being worked on. Next I resized it to 1920 pixels in resizing image the other dimension would be automatic. Then I took it to canvas image resize and made both dimensions the same 1920x1920 and saved it as a .jpg file. This gives the viewer a comparison to a square of any dimension.
Charlie /:)#