Patent ID: 6141455
Filing Date: 2000-10-31
Classification: H04N

Abstract:
An image encoding apparatus comprising:an image sensing element for providing a series of voltage signals corresponding to a two-dimensional image;a two-dimensional analog discrete cosine transform circuit for performing, in pixel blocks, a two-dimensional discrete cosine transform on said series of voltage signals supplied from said image sensing element; anda quantization circuit for converting a voltage representing a result of said two-dimensional discrete cosine transform carried out by said two-dimensional analog discrete cosine transform circuit into a digital value according to a given quantization coefficient Q=2.sup.N .multidot.S (1.ltoreq.S<2) wherein a voltage S.multidot.Vref that is S times greater than a fixed voltage Vref serves as a reference voltage, and for right-shifting said digital value N bits in order to quantize said two-dimensional discrete cosine transform result, N being greater than or equal to zero,said two-dimensional analog discrete cosine transform circuit comprising:a row of analog sum-of products arithmetic units for performing a one dimensional discrete cosine transform; andan analog memory array for holding a series of output voltage signals of said row of analog sum-of-products arithmetic units corresponding to said series of voltage signals from said image sensing element, and for providing a series of voltage signals obtained by transposing a matrix formed of said series of output voltage signals to said row of analog sum-of-products arithmetic units,each of said analog sum-of-products arithmetic units comprising:a plurality of capacitors having respective weights for corresponding elements of a one-dimensional discrete cosine transform matrix;a row of switches for providing an input voltage signal to each of said capacitors; and;an addition operation circuit for summing voltages held in said plurality of capacitors.