Re: Floating point pixel data / image handling confusion
Re: Floating point pixel data / image handling confusion
- Subject: Re: Floating point pixel data / image handling confusion
- From: "Adam R. Maxwell" <email@hidden>
- Date: Mon, 10 Nov 2008 18:11:39 -0800
On Nov 10, 2008, at 4:53 AM, Felix Ulber wrote:
I am working on an Cocoa Application whose main purpose is to display
some stuff in OpenGL.
In conjunction with that I need to be able to read in floating point
images (most likely from an exr file) and resize them. Unfortunately,
with NSImage and NSBitmapImage it seems I can get only 32 bpp/8bit per
channel bitmap data (as the example in the cocoa drawing guide).
I'm not familiar with exr, but NSBitmapImageRep does support floating
point images; I use it to read 32-bit float GeoTIFF files. See
NSFloatingPointSamplesBitmapFormat from the NSBitmapFormat enum, or
the Quartz docs for bitmap contexts (Table 2-1):
http://developer.apple.com/documentation/GraphicsImaging/Conceptual/drawingwithquartz2d/dq_context/chapter_3_section_4.html
So I did some research and stumbled upon things like Image I/O, Core
Image and vImage. But I have tom admit have absolutely no clue what to
use when and how.
The easiest way to scale your image is probably to create a new bitmap
context of the desired size and pixel format, draw the original image
into it, then use the pixel data from your new context. You can
either use NSImage/NSBitmapImageRep or Quartz 2D for that.
http://developer.apple.com/documentation/GraphicsImaging/Conceptual/OpenGL-MacProgGuide/opengl_texturedata/chapter_10_section_5.html
Core Image would work as well, but I think getting the pixel data is
more roundabout. I wouldn't recommend vImage if you're not familiar
with the higher level frameworks.
--
Adam
Attachment:
smime.p7s
Description: S/MIME cryptographic signature
_______________________________________________
Cocoa-dev mailing list (email@hidden)
Please do not post admin requests or moderator comments to the list.
Contact the moderators at cocoa-dev-admins(at)lists.apple.com
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden