Re: 16 bit integer per colour bitmap graphics context

Subject: Re: 16 bit integer per colour bitmap graphics context

From: Derek Clegg <email@hidden>

Date: Thu, 12 May 2005 16:14:44 -0700

Delivered-to: email@hidden

On May 12, 2005, at 2:07 PM, Martin Greenwood wrote:

This article suggests that 16bit per colour (b48r or b64a) images are supported by Quartz 2D.

http://developer.apple.com/qa/qa2001/qa1114.html

Yes, images with 16 bits/component are supported.

Whereas Table 2.1 here suggests that 8bit is the largest size for a colour.

Also true: a bitmap context is not the same thing as an image.

http://developer.apple.com/documentation/GraphicsImaging/Conceptual/drawingwithquartz2d/dq_context/chapter_3_section_4.html

When I try to create a bitmap graphics context the following happens..

CGBitmapContextCreate: unsupported parameter combination: 16 integer bits/component; 48 bits/pixel; 3-component colorspace; kCGImageAlphaNone.
or
CGBitmapContextCreate: unsupported parameter combination: 16 integer bits/component; 64 bits/pixel; 3-component colorspace; kCGImageAlphaPremultipliedLast.

Can I use Quartz to draw into b48r or b64a bitmaps?

No, you cannot. There's no support for > 8 bits/component (integer) bitmap contexts.

Derek

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References:
	>16 bit integer per colour bitmap graphics context (From: Martin Greenwood <email@hidden>)