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Re: cgBlendImage, more than 2 images? [message #90717 is a reply to message #90716]

Thu, 02 April 2015 09:40

Michael Galloy
Messages: 1114
Registered: April 2006

Senior Member

On 4/2/15 8:25 AM, sam.tushaus@gmail.com wrote:
> Hello! I was wondering if anyone had tried using cgBlendImage to
> blend more than 2 images. I have 4 images - I've tried blending 2 of
> the images, blending the other 2, and blending those together, but
> I've had no luck thus far. Has anyone tried this? Should I simply
> stick with two separate blended images instead?

I don't know the details of cgBlendImage, but if you want to blend four
images like:

I = a * I1 + b * I2 + c * I3 + d * I4

where a + b + c + d = 1, then you should blend the first two images
together to get I12:

I12 = a / (a + b) * I1 + b / (a + b) I2

Blend images 3 and 4 to get I34:

I34 = c / (c + d) * I3 + d / (c + d) I4

Then blend the I12 and I34 to get the result:

I = (a + b) / (a + b + c + d) * I12 + (c + d) / (a + b + c + d) * I34

Is that what you are doing?

-Mike

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[Message index]

		cgBlendImage, more than 2 images? By: sam.tushaus on Thu, 02 April 2015 07:25
		Re: cgBlendImage, more than 2 images? By: Michael Galloy on Thu, 02 April 2015 09:40
		Re: cgBlendImage, more than 2 images? By: sam.tushaus on Thu, 02 April 2015 10:11
		Re: cgBlendImage, more than 2 images? By: David Fanning on Thu, 02 April 2015 17:02

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