Legacy ImageMagick Discussions Archive

I am trying to convert an image to a 16 bit color depth, and I can't seem to figure it out. The image that I'm starting with is a jpg.

convert -depth 6 image.jpg image.bmp

but every time, the bmp is TrueColor, and 24 bits. I want to make the bmp for a 16 bit LCD, but I can't seem to figure out the convert program. Anyone would could offer a tip, I'd greatly appreciate it.


Info from the identify:

jpg info:
Image: image.jpg
Format: JPEG (Joint Photographic Experts Group JFIF format)
Class: DirectClass
Geometry: 755x1200
Type: TrueColor
Endianess: Undefined
Colorspace: RGB
Channel depth:
Red: 8-bits
Green: 8-bits
Blue: 8-bits
Channel statistics:
Red:
Min: 0 (0)
Max: 255 (1)
Mean: 221.573 (0.868915)
Standard deviation: 57.8563 (0.226887)
Green:
Min: 0 (0)
Max: 255 (1)
Mean: 220.679 (0.865407)
Standard deviation: 53.5961 (0.210181)
Blue:
Min: 0 (0)
Max: 255 (1)
Mean: 184.951 (0.725297)
Standard deviation: 93.7735 (0.367739)



bmp info:
Image: image.bmp
Format: BMP (Microsoft Windows bitmap image)
Class: DirectClass
Geometry: 755x1200
Type: TrueColor
Endianess: Undefined
Colorspace: RGB
Channel depth:
Red: 8-bits
Green: 8-bits
Blue: 8-bits
Channel statistics:
Red:
Min: 0 (0)
Max: 255 (1)
Mean: 221.573 (0.868915)
Standard deviation: 57.8563 (0.226887)
Green:
Min: 0 (0)
Max: 255 (1)
Mean: 220.679 (0.865407)
Standard deviation: 53.5961 (0.210181)
Blue:
Min: 0 (0)
Max: 255 (1)
Mean: 184.951 (0.725297)
Standard deviation: 93.7735 (0.367739)

try using BMP2 and BMP3 file formats. One of these may do the job.

They don't seem to change the color depth. Tried BMP2 and BMP3. Even converting them to a PNG8 (which reduced it to 8 bit color) then to a bmp brings it back to 32 bit color. The closest I got was

convert -colors 256 image.jpg BMP2:image.bmp
===> 8 bit color


convert -colors 257 image.jpg BMP2:image.bmp
====> 24 bit color


I'm not sure what 16 bit color is (color per pixel, channel) but I can't seem to figure this out. I've tried about 300 combinations by now

It may be a unsupported format. It may need to be reported as a request on the bugs forum. A link to an example 16bit BMP image may also help get it done faster.

By 16 do you mean 16 bits per RGB color, using some psuedo-color method,
or 16 bits per color value? Be clear.

From my notes...
ImageMagick supports 8, 24, and 32-bit BMP images.

EG: 8bit palette, and 8bit per value, RGB or RGBA

This was the color depth I was looking for. This description was from wikipedia. I'm looking for an example file for this color depth.

16-bit color uses 5 bits to represent red, 5 bits to represent blue, but (since the human eye is more sensitive to the color green) uses 6 bits to represent 64 levels of green. These can therefore be combined to give 65,536 (32 × 64 × 32) mixed colors. Sixteen-bit color is referred to as "thousands of colors" on Macintosh systems.

I don't think that is implemented in IM. You could request it (with a link to an image example that is using it) but I think that is all. I don't think even the NetPBM BMP converter can do this.