Detection circuit and signal compression method

A detection circuit comprising:

• a plurality of detection elements arranged in a matrix form;
• a plurality of scanning lines that extend in a first direction and are arranged in a second direction intersecting the first direction, the scanning lines being connected to a scan circuit;
• a plurality of signal lines that extend in the second direction and are arranged in the first direction, the signal lines being connected to a detection circuit;
• and
• a control circuit, wherein
• each of the plurality of detection elements is connected to a corresponding scanning line and a corresponding signal line,
• the detection circuit is configured to sequentially read out detection values of signals of the plurality of detection elements through the plurality of signal lines, and
• the control circuit, when externally outputting a detection value of a signal of a detection element of interest, outputs, as transmission difference data, difference data between a value based on a detection value of a signal of a detection element read out before a detection timing of the detection value of the signal of the detection element of interest and the detection value of the signal of the detection element of interest.