Re: How to get image real number of bits per pixel
Re: How to get image real number of bits per pixel
- Subject: Re: How to get image real number of bits per pixel
- From: Marco Binder <email@hidden>
- Date: Thu, 27 Feb 2003 13:10:12 +0100
I m sorry, I thought you were talking of TIFF images. I ve neer used
bmp files and I could imagine, that such files are in deed converted to
24 or 32 bit images during "importing" into an NSBitmapImageRep. But:
thats plain speculation. Sorry I cant be of real help...
marco
Am Donnerstag, 27.02.03 um 10:07 Uhr schrieb Sebastien TOPIN:
Thanks for your help,
Maybe I am doing something wrong, but when I try to check the
colorSpaceName
on my NSBitmapImageRep, I get a "NSCalibratedRGBColorSpace" which is
the
default value and does not tell me that this is a grayscale 8 bits
picture.
Here is a part of my code:
//========================================
NSBitmapImageRep *myImageRep = [NSBitmapImageRep
imageRepWithContentsOfFile:@"myGrayscaleFile.bmp"];
NSString *myColorNameSpace = [myImageRep colorSpaceName];
int iBitsPerPixel = [myImageRep bitsPerPixel];
...
//========================================
and I get:
colorSpaceName = "NSCalibratedRGBColorSpace"
iBitsPerPixel = "24"
I start to wonder if I going to be able to do this simple thing with
Cocoa...?
Seb
----- Original Message -----
From: "Jeff Disher" <email@hidden>
To: "Sebastien TOPIN" <email@hidden>
Sent: Thursday, February 27, 2003 3:01 AM
Subject: Re: How to get image real number of bits per pixel
Get the colour space name of the NSBitmapImageRep to make sure that it
actually is a grayscale image. I know that I have been able to open
grayscale GIFs and correctly get the number of bits per pixel but they
do report as being in the white colour space.
This way you can at least find out what colour space it is loaded
into.
Just an idea,
Jeff.
On Wednesday, February 26, 2003, at 10:04 AM, Sebastien TOPIN wrote:
I am still not able to get the "real" number of bits per pixel from
my
bmp
image.
I tried to create an NSBitmapImageRep object from [NSBitmapImageRep
WithContentOfFile:filename] and when I check the bitsPerPixel or
samplePerPixel value I still have 24 or 32 for a 8 bits gray scale
image.
Do I have to use QuickTime component to get this kind of information
or is
there a way to do it with Cocoa?
BTW, I am new to Cocoa (and even to Mac I was on Visual Studio last
week!)
and I do apologise in advance if I ask stupid questions...
Seb
----- Original Message -----
From: "Marco Binder" <email@hidden>
To: "Sebastien TOPIN" <email@hidden>
Cc: "Cocoa List" <email@hidden>
Sent: Tuesday, February 25, 2003 6:25 PM
Subject: Re: How to get image real number of bits per pixel
I guess you can ask the NSImageView for the path of the dropped file
(please see docs yourself- I m busy at the moment). With the path,
you
can then instantiate a new NSBitmapImageRep. I know, this is waste
of
memory (TWO bitmap reps of the same image), but I could not yet
figure
out another way. You could of course subclass NSImageView and
intercept
the file-drop. Then set up a NSBitmapImageRep and add it to a newly
created NSImage. Supply then this image as an argument when calling
[myImageViewObject setImage:newlyCreatedImage].
marco
Am Dienstag, 25.02.03 um 18:14 Uhr schrieb Sebastien TOPIN:
Thanks but how do you get the image data? Is it directly from the
file?
I was trying to use the drag'n drop functionality (drag an image
from
the
Finder to your application image control) in order to open my image
file. In
this case I already get an instantiated NSBitmapImageRep from
NSImageView
and just extract its parameters. This is what gives me the 32 bits
per
pixel.
----- Original Message -----
From: "Marco Binder" <email@hidden>
To: "Sebastien TOPIN" <email@hidden>
Cc: <email@hidden>
Sent: Tuesday, February 25, 2003 5:57 PM
Subject: Re: How to get image real number of bits per pixel
Directly instantiate an NSBitmapImageRep with the image-data and
call
the method. As to my experience, Cocoa will always use 8-bit RGBA
to
display images in an NSImageView.
marco
Am Dienstag, 25.02.03 um 17:21 Uhr schrieb Sebastien TOPIN:
Hi Folks,
I am trying to get the real number of bits per pixel for a
displayed
image.
A NSImageView object enables me to drag n' drop a bmp image from
the
Finder
and display it in my app.
Then I got an NSBitmapImageRep from the NSImageView and did that:
int iBitsPerPix = [bittmapImageRep bitsPerPixel];
The result is always 32 even for grayscale 8 bits per pixel
images
or
24 bits
per pixel color images.
How can I get the image real number of bits per pixel of those
images?
Thanks in advance,
Seb
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BINDER
_____________________________________________________
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Jeff Disher
President and Lead Developer of Spectral Class
Spectral Class: Shedding Light on Innovation
http://www.spectralclass.com/
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| \/ | Telefon: 07531 / 94 19 94 Fax: 07531 / 94 19 92
| |ARCO Snail-Mail: Banater Str. 3 - 78467 Konstanz
BINDER _____________________________________________________
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