Transform coefficient coding method and device therefor

An image encoding method performed by an encoding apparatus, the method comprising:

• deriving a transform coefficient based on a residual sample for a current block;
• and
• encoding residual information including information on the transform coefficient,
• wherein the residual information includes a context-based coded context syntax element,
• wherein the deriving the transform coefficients encodes context syntax elements based on a context, wherein the context syntax elements are coded based on the context;
• wherein the context syntax elements are encoded based on a maximum value of context-coded bins for the current block, and
• wherein the maximum value is determined based on a specific region which a last significant coefficient of the current block is in.

A non-transitory computer-readable storage medium storing encoded information generated by an encoding method, the encoding method comprising:

• receiving a bitstream including residual information;
• deriving a transform coefficient for a current block based on the residual information;
• and
• deriving a residual sample for the current block based on the transform coefficient;
• wherein the deriving the transform coefficients decodes context syntax elements based on a context, wherein the context syntax elements are coded based on the context;
• wherein the context syntax elements are decoded based on a maximum value of context-coded bins for the current block, and
• wherein the maximum value is determined based on a specific region which a last significant coefficient of the current block is in.