23-05-2017, 06:20 PM

Hi Cardigan

Thanks for the link, I hadn't taken notice of test card J before.

Hi Jeffery

I think the shape the cosine puts on the aperture makes little difference but the "lift" appears to be important.

I am using coefficients that 8 bits wide and first tried a aperture that was purely cosine in shape. The coefficients ranged from 0 to 254. The results were disappointing to say the least. I then tried introducing lift and am now using a lift of 51 with the coefficients ranging from 51 to 203. The lift made an huge difference. I guess that makes sense as a 405 line is wider than a 625 one so will always contain information from more than one line even if the 405 line lies directly on top of a 625 one. It makes sense now but I hadn't thought of it that way before.

Frank

Thanks for the link, I hadn't taken notice of test card J before.

Hi Jeffery

I think the shape the cosine puts on the aperture makes little difference but the "lift" appears to be important.

I am using coefficients that 8 bits wide and first tried a aperture that was purely cosine in shape. The coefficients ranged from 0 to 254. The results were disappointing to say the least. I then tried introducing lift and am now using a lift of 51 with the coefficients ranging from 51 to 203. The lift made an huge difference. I guess that makes sense as a 405 line is wider than a 625 one so will always contain information from more than one line even if the 405 line lies directly on top of a 625 one. It makes sense now but I hadn't thought of it that way before.

Frank