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Message: <blockquote data-quote="jawbroken" data-source="post: 70885" data-attributes="member: 14372">Okay, I have something that works well, I think. It will be easy enough to code as a lookup array once a number of sample points is decided upon.I started with a cubic, but that was too flat around the mid point. So I used the inverse sin function, which is not too flat, but still clusters points in the centre of the screen.For, say, number of samples = 21 (n=21):f<img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite25" alt="(n)" title="Thumbs Down    (n)" loading="lazy" data-shortname="(n)" /> = arcsin((n-10)/10)*0.8/pi + 0.5For n is from 0 to 21, f<img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite25" alt="(n)" title="Thumbs Down    (n)" loading="lazy" data-shortname="(n)" /> ranges from 0.1 to 0.9 (to avoid sampling out of frame or disinteresting areas).To adapt for a different number of samples the (n-10)/10 part is changed to give a range from -1 to 1 for n from 0 to maxN.For above:f<img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite25" alt="(n)" title="Thumbs Down    (n)" loading="lazy" data-shortname="(n)" /> = [0.10000, 0.21485, 0.26387, 0.30255, 0.33613, 0.36667, 0.39521, 0.42241, 0.44872, 0.47449, 0.50000, 0.52551, 0.55128, 0.57759, 0.60479, 0.63333, 0.66387, 0.69745, 0.73613, 0.78515, 0.90000]Then all you need to do is multiple by the width or height and truncate or round to an integer to get the sample pixel. For example, looking at a 720x576 frame, sample points along the row will mean multiplying by 720, giving points at:sample points = [72, 155, 190, 218, 242, 264, 285, 304, 323, 342, 360, 378, 397, 416, 435, 456, 478, 502, 530, 565, 648]or for columns, multiply by 576 giving:sample points = [72, 155, 190, 218, 242, 264, 285, 304, 323, 342, 360, 378, 397, 416, 435, 456, 478, 502, 530, 565, 648]</blockquote>

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