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SWT ImageData -- How to obtain number of channels? [message #527944]

Sat, 17 April 2010 07:55

JIA Pei

Messages: 49
Registered: September 2009

Member

Hi, all:

I'm wondering how I can obtain the number of channels for a loaded image, using SWT technology.

Let's have a look at the following website first.
http://www.eclipse.org/articles/Article-SWT-images/graphics- resources.html#ImageData

By using

ImageData ideaImageData = new ImageData(
    getClass().getResourceAsStream("Idea.jpg"));

we loaded an image and stored in

ImageData ideaImageDat

In Eclipse' documentation at
http://help.eclipse.org/galileo/index.jsp?topic=/org.eclipse .platform.doc.isv/reference/api/overview-summary.html

Nothing can be found to tell "number of image channels", in the class "ImageData".

What I would like to find is something like a function getNbOfChannels();

If the loaded image "idea.jpg" is a color image, then, the function returns 3
If it is a gray image, then, the function returns 1.

Can anybody help to give me a hand ?

Cheers
JIA Pei

[Updated on: Sat, 17 April 2010 07:58]

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Re: SWT ImageData -- How to obtain number of channels? [message #527967 is a reply to message #527944]

Sat, 17 April 2010 16:06

Ralf Ebert

Messages: 168
Registered: July 2009

Senior Member

Hi JIA Pei,

> I'm wondering how I can obtain the number of channels for a loaded
> image, using SWT technology.

see ImageData#depth.

- Ralf

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Re: SWT ImageData -- How to obtain number of channels? [message #527970 is a reply to message #527967]

Sat, 17 April 2010 16:52

JIA Pei

Messages: 49
Registered: September 2009

Member

Hi, Dear Ralf:

Thank you very much for you prompt reply !!

Now, I'm using

int NbOfChannels	= iImg.bytesPerLine/iImg.width;

but, I've got no idea whether it's correct or not.

As for depth, in my case, it's always 8. (that's why I think "bytesPerLine" might be able to work)
But, that only relates to number of bits used for a single channel of a pixel.
Namely, if I'm using 3 channels for a pixel, that will cost 3*8=24 bits.

In this case:
depth = 8
NbOfChannels=3

How do you think of it? ^_^

Thank you very much.

Best Regards
JIA

Ralf Ebert wrote on Sat, 17 April 2010 12:06

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