I have an image with alpha channel, I need to save it as 32-bit BMP. However, mspaint doesn't allow saving as 32-bit, only 24-bit. I have Photoshop CS5, but it doesn't have the option to save as 32-bit BMP also.
Photoshop >> Menu >> File >> Save As >> Choose format BMP in dropdown box >> Save button >> Choose 32-bit format >> OK button
However, photoshop will save the image as XRGB. In case the image has alpha channel (as ARGB), must use another tool: