topic Re: Need an example on ippiAlphaComp in Intel® Integrated Performance Primitives

Need an example on ippiAlphaComp

udi — Wed, 14 Dec 2005 17:58:58 GMT

Hi,
I have 2 32bit ( 4channels ) images.

I tried to compose a new image, I wanted the first image will be the background the second will be a semi transparent foregroung.

Everything I did, didn't work.

Any code example somewhere ?

Thanks in advance.

Udi Raz

Re: Need an example on ippiAlphaComp

Vladimir_Dudnik — Sat, 17 Dec 2005 02:46:27 GMT

Dear Udi,

could you please take a look on IPP manual you get within IPP installation? For example, ippiman.pdf, chapter5 Image Arithmetic and Logical Operations, article Alpha Composition describes in some details ippiAlphaComp functions and contains simple sample how to call this function:

Code:

IppStatus acomp( void ) {
Ipp8u imga[8*8], imgb[8*8], imgc[8*8];
IppiSize roi = { 8, 8 };
IppStatus st;
ippiImageRamp_8u_C1R( imga, 8, roi, 0, 1, ippAxsHorizontal );
ippiImageRamp_8u_C1R( imgb, 8, roi, 0, 2, ippAxsHorizontal );
st = ippiAlphaCompC_8u_C1R( imga, 8, 255/3, imgb, 8, 255, imgc, 8, roi,
ippAlphaOver );
printf( "over: a=%d,A=255/3; b=%d,B=255; c=%d //
c=a*A+b*(1-A)*B
",imga[6],imgb[6],imgc[6] );
return st;
}
Output
over: a=6,A=255/3; b=12,B=255; c=10 // c=a*A+b*B*(1-A)

Regards,
Vladimir

Re: Need an example on ippiAlphaComp

jiangdingfeng — Tue, 24 Jun 2008 03:50:22 GMT

Hi,I also tired to compose 4 images(YUV420,cif) to a new image(YUV420,4cif),I wanted each image display a quarter in new image.

But I don't know how to do it by IPP lib.Can ereryone tell me?Thank you very much!

Re: Need an example on ippiAlphaComp

Vladimir_Dudnik — Tue, 24 Jun 2008 13:44:27 GMT

It seems for me that you are talking about different thing. As far as I get it you want to copy four small images in one place in such a way to form new and bigger image rather than do alpha blending, discussed in this thread. Is that correct?

Vladimir