Can't Convert grayscale bmp to color jpg

[abinns]

Using 64-bit Windows Server 2008 R2 Standard, and ImageMagick 6.6.9-Q16

Using the command-line tool with this statement:

mogrify -format jpg -colors 256 -type Bilevel [filename].bmp

The original colorspace is RGB. Original depth is 8. These values are retained when the image is converted. I have tried -type Palette, -type TrueColor. I have tried specifying colorspace and depth, although these are correct originally. Please advise. Thank you.

[snibgo]

I don't understand what problem you have.

"-type bilevel" should reduce the colours to 2 (black and white), so "-colors 256" is pointless.

Your version of IM is very old.

[abinns]

That is interesting. When I save the bmp as 256-color bmp, and run -identify against the resulting file, it shows Type and Base Type as "Bilevel", which is the reason I added that specification. I am hesitant to upgrade because we have other processes using the current version. Would an upgrade help?

[snibgo]

Would an upgrade help what? What problem are you trying to solve? What is going wrong?

[abinns]

I am asking if upgrading would help to resolve the problem I originally posted. No matter what specs I try, I cannot find a way to produce a 256 color jpg from a Bilevel, RGB, 8-bit depth .bmp image. The Type and Base Type always come out as Grayscale in the resulting jpg file. I am using Mogrify, not Convert.

[snibgo]

As far as I know, "a 256 color jpg" doesn't exist. JPEGs have essentially two formats: 8-bit greyscale, and 3x8-bit colour. If your image has colours, it will become a 24-bit JPEG. If it has no colours it will become a greyscale JPEG.

[abinns]

You can probably tell by now I'm no graphics expert! I appreciate your help. Are you saying that regardless what command-line specification I set, if the image has no basic color in it but black, that it is going to come out as Grayscale? If so, then setting specifications is the real issue. For my purpose, an uncompressed 1-bit tif in black and white is also acceptable. However, I am having a similar problem setting a specification for that also, because the resulting file continues to show colorspace = RGB even though I specified -colorspace "Gray". Tell me, do the values we want to assign to the specifications have to be enclosed in quotes?

[snibgo]

If your image has only black and white, then "-format tiff" in mogrify should create an uncompressed 1-bit tiff. It does for me, IM v6.8.9-0 on Windows 8.1.