Deinterlacing 1080i HDTV for 1080p displays

[Rodolfo]

Jjkilleen,

I believe your original question was not responded as fully as you illustrated on your statement.

1080i has two fields of 540 lines each appearing every 60th of second to make one frame. In the progressive display world we live today each 1080 frame is displayed at once (not per field as CRT).

If the set is a 720p, or 768 panel, etc then there is scaling that take place in addition to the processing statements I include below, so to keep it simple, in a world of more 1080p sets that we imagined, I will cover 1080p displays upconverting from 1080i.

There are (MANY) TVs that take each incoming field of 540 lines and complete the remaining 540 lines of the 1080 frame to be shown with video processing, and shoot the 1080 lines-frame in 1/60 (the speed of the field).

In this case half of the pixels of the frame are calculated and interpolated within the image, there were not present in the original image. This type of interpolation is an art, there are good painters, but there are also many bad painters around.

Imagine using Photoshop to blow up a photo, finding that it is now too grainy because is missing pixels, and you go with the touch tool and start inventing pixels, half of the whole picture. Even if that picture frame could have been done to perfection, imagine now another 59 pictures right behind that one, all within one second.

Perfection has a limit, and also is rare, and most manufacturers are not looking for perfection, they like revenue, the sooner the better, so another model can be sold again 3 months from now, even to the same person.

There are other TVs that actually interleave both 540 fields into the same 1080 frame, then shoot that whole frame at 1/60, and display again the exact same (repeated) frame in the next 1/60. The following 1/60 will contain a frame made with the next two new incoming fields, and repeat that one again at the next 1/60, and so on.

In that case, one has to remember that the 540 lines of each field record an instant in time of pixels that come from a different position than the next field. Objects in the image in front the camera are recorded in halves, and they could have moved during the short interval of each field recording, putting those two together without any adaptive video processing could be perceived as lower resolution and blurriness.

There are TVs that combine both techniques depending on the area of the image, if the image is not moving much, like a fixed picture of the blue sky or the grass of a golf course with a camera shot that did not move, then such area could afford calculated pixels. The area of the image recording the golfer

[Richard]

Thanks Rodolfo for your time and effort!

[jjkilleen]

Thank you all for your most informative posts. Clearly, this is a very complex and interesting subject.