Sunday, January 17, 2016

export - How to save a file as a bitmap in Photoshop?


I'm using (or trying to use) Photoshop CC (14.2.1 x64) to produce small bitmaps for a .Net Micro Framework device. Memory is at a premium so I need to produce the screen assets in 16 bit RGB 565 format.


I have my document set up in RGB (I've tried RGB 32 and RGB 16) but when I come to "save as" bitmap / bmp is not one of the available options. Most help articles I've found online suggest that this is solved be using RGB not CYMK, but as you can see from the screenshots below, it has not fixed it for me.


Where is BMP in the 'Save As' list?



How can I save a file as .BMP in Photoshop CC?


PSScreenshot


PSScreenshot



Answer



I believe bmp only supports 8 bit RGB (24bit images)


Things can get confusing when dealing with the word "bit" at times.


By Adobe definitions.....


8 bit RGB = 24bit image (8 bits R, 8 bits G, 8 bits B = 24).


16 bit RGB = 48bit image (16 bits R, 16 bits G, 16 bits B = 48).


Using these numbers, standard RGB images are referred to as 8 or 24 bit. 16 bit refers to an RGB image with more than normal color depth.



Photoshop has the ability to work with 8, 16, or 32 bit RGB, which translates to 24, 48 or 96 bit images. However, most non-photo software (web browsers) utilize 24bit RGB images and often don't support the 48 or 96 bit images.


To further confuse matters, you can have an additional bit depth for transparency. For example a 32bit Image can refer to a 24bit image + 8 bits of alpha (transparency). [BMP doesn't support transparency so it can't save 32bit images either]


Additional Note: As pointed out this Question shows how to save an RGB565 bmp image with Photoshop. But you still have to start with a 24 bit image.


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