Elementary cell of a linear filter for image processing

Elementary cell (1;

• 61, 71, 81, 91;
• 261, 271, 281, 291) of a linear filter for image processing, comprising:
• an input (2), intended to sequentially receive data relating to pixels of an image to be processed,
• a circulation output (3), intended to sequentially transmit the said data with a delay,
• a calculation output (4), intended to sequentially transmit results obtained by a processing of the said data in the said cell (1;
• 61, 71, 81, 91;
• 261, 271, 281, 291),
• a main delay line (5) having an input capable of being linked to the input (2) of the cell and an output capable of being linked to the circulation output (3) and to the calculation output (4) of the cell,
• a coefficients memory (9), provided so as to contain at least one multiplier coefficient, and
• a multiplier (8) connected to the coefficients memory (9), having an input (24) and an output (26) which are capable of being linked respectively to the output of the main delay line (5) and to the calculation output (4) of the cell, the said multiplier (8) being intended to perform multiplications on the said data received at the input of the said multiplier by at least one of the said multiplier coefficients of the coefficients memory (9) and to transmit via the output (26) of the said multiplier (8) the result obtained,
• characterized in that the main delay line (5) is capable of producing a maximum shift corresponding to at least two pixels of the image to be processed and in that the said cell (1;
• 61, 71, 81, 91;
• 261, 271, 281, 291) also comprises:
• an auxiliary delay line (6) having an input and an output which are capable of being linked respectively to the input (2) of the cell and to the circulation output (3) of the cell,
• an adder (7) having a first and a second input (21, 22) which are capable of being linked respectively to the input (2) of the cell and to the output of the main delay line (5), and an output (23) capable of being linked to the multiplier (8),
• delay line selection means (MUX4) having a first and a second state, the said means being intended to link the input (2) of the cell to the circulation output (3) of the cell by way of the main delay line (5) in the first state and by way of the auxiliary delay line (6) in the second state,
• and calculation selection means (MUX1, MUX2) having at least two states, the said means being intended to link the input (2) of the cell and/or the output of the said main delay line (5) to the corresponding inputs (21, 22) of the adder (7), in the said states respectively.