I simply averaged the rgb in the provided example, but Anton's
solution for computing the luminosity is much better (at least for
humans).
.xX
On Aug 4, 2008, at 1:20 PM, vade wrote:
he mean externally form the javascript patch. Computer the luma by
converting to black and white, or use rec709 luma values in a
CIKernel, and get the area average, and pass that into the JS.
I think external reffered to outside the JS patch, not outside QC :)
CI kernel for rec 709 luma coefficients (as per HDTV spec):
/* luma coeffs Y' = 0.2126 R' + 0.7152 G' + 0.0722 B */
const vec3 lumacoeff = vec3(0.2126,0.7152,0.0722);
kernel vec4 lumaKernel(sampler image)
{
vec4 inputImage = sample(image, samplerCoord(image));
float luma = dot(inputImage.rgb, lumacoeff);
return vec4(luma,luma,luma,inputImage.a);
}
On Aug 4, 2008, at 4:14 PM, Alex Drinkwater wrote:
On 4 Aug 2008, at 21:10, Alessandro Sabatelli wrote:
Create an object:
var myObject = new Object()
Then add the image and the brightness, which you can compute
externally:
That's the point though:
he wants to compute the brightness IN Quartz Composer.
a|x
http://machinesdontcare.wordpress.com
myObject.image = image
myObject.brightness = brightness
Then store the image in an array
myArray[index] = myObject
Once you've downloaded and processed all of the images then sort
myArray.sort(f)
Where f simply compares the brightness
function f(a, b) {
return a.brightness-b.brightness
}
Here's an example which shows it working:
<Brightness Sort.qtz>
.xX
On Aug 3, 2008, at 1:58 PM, aienn wrote:
On Aug 4, 2008, at 12:12 AM, Alessandro Sabatelli wrote:
You can store the average brightness along with the image and
then return the sorted list of images from JS.
Yep, I already figured out the JS and averaging stuff, but how
exactly do I store the average brightness along with the image,
as you're suggesting?
a.
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