HDTV to conventional TV signal converting apparatus with non-linear level correction
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorsYoshio Seki, Atsushi Ishizu, Masaki Tokoi
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Abstract
A television signal converting apparatus receives a high definition television signal which is processed approximately linearly on the transmission and receiving sides and whose transmission only is processed non-linearly. A non-linear level correction circuit is provided, which collectively simultaneously carries out two kinds of non-linear processes, namely, a transmission inverse gamma correction and a CRT gamma correction, which are executed on the transmission side, thus precisely reproducing the signal level of a luminance signal by using a small-scale circuit.
Claims6
A television signal converting apparatus for converting a high-definition television signal having a larger number of scanning lines than that of a conventional television signal into the conventional television signal, said high definition television signal having been bandwidth compressed and processed so as to have a non-linear level expansion characteristic at a transmission side and transmitted from the transmission side in the form of a band-compressed television signal, said apparatus comprising:
- a non-linear correction means for correcting a signal level of the transmitted band-compressed television signal based on a predetermined non-linear characteristic;
- a signal converting means for converting an output signal of said non-linear correction means to the conventional television signal, said signal converting means comprising an interpolation means coupled to said non-linear correction means for interpolating the band-compressed television signal to restore the high-definition television signal, and a scanning line density converting means for changing the number of scanning lines of the high-definition television signal restored by said interpolation means to the number of scanning lines of the conventional television signal;
- an inverse matrix means coupled to said signal converting means for producing three primary color signals from an output signal of said scanning line density converting means;
- and
- a picture display means coupled to said inverse matrix means for displaying the three primary signals;
- wherein said non-linear level correction means corrects for a difference between said non-linear level expansion characteristic and a non-linear electro-optic conversion characteristic of said picture display means.
A television signal converting apparatus for converting a high-definition television signal having a larger number of scanning lines than that of a conventional television signal into the conventional television signal, said high definition television signal having been bandwidth compressed and processed so as to have a non-linear level expansion characteristic at a transmission side and transmitted through a transmission path from the transmission side in the form of a band-compressed television signal, said apparatus comprising:
- a non-linear correction means for correcting a signal level of the transmitted band-compressed television signal based on a predetermined non-linear characteristic;
- a signal converting means for converting an output signal of said non-linear correction means to the conventional television signal, said signal converting means comprising an interpolation means coupled to said non-linear correction means for interpolating the band-compressed television signal to restore the high-definition television signal, and a scanning line density converting means for changing the number of scanning lines of the high-definition television signal restored by said interpolation means to the number of scanning lines of the conventional television signal;
- an inverse matrix means coupled to said signal converting means for producing three primary color signals from an output signal of said scanning line density converting means;
- and
- a picture display means coupled to said inverse matrix means for displaying the three primary signals;
- wherein said non-linear level correction means corrects a transmission gamma of the transmission path and a gamma of said picture display means at the same time by one predetermined correction value.
Dependencies are inferred from the claim text.