Image encoding/decoding method and device

An image encoding method, comprising:

• determining an intra prediction mode of a chroma block;
• determining a neighboring region for inter-component reference of the chroma block, the neighboring region including at least one of a top neighboring region or a left neighboring region adjacent to a luma block corresponding to the chroma block;
• deriving down-sampled neighboring luma samples by down-sampling neighboring luma samples in the neighboring region,
• deriving a parameter for the inter-component reference of the chroma block based on the down-sampled neighboring luma samples;
• and
• predicting the chroma block based on the parameter for the inter-component reference,
• wherein deriving the parameter for the inter-component reference comprises:
• classifying the down-sampled neighboring luma samples into a first group and a second group, the first group including down-sampled neighboring luma samples having relatively large values and the second group including down-sampled neighboring luma samples having relatively small values;
• and
• calculating a maximum value by averaging the down-sampled neighboring luma samples included in the first group and a minimum value by averaging the down-sampled neighboring luma samples included in the second group,
• wherein the parameter for the inter-component reference is derived based on a difference between the maximum value and the minimum value,
• wherein when the top neighboring region belongs to a different coding tree unit from the luma block, only three neighboring luma samples are used to derive one down-sample neighboring luma sample, and
• wherein when the top neighboring region belongs to a same coding tree unit as the luma block, five or six neighboring luma samples are used to derive the one down-sample neighboring luma sample.

A non-transitory computer-readable medium storing a bitstream generated by an image encoding method, the image encoding method comprising:

• determining an intra prediction mode of a chroma block based on the intra prediction mode;
• determining a neighboring region for inter-component reference of the chroma block, the neighboring region including at least one of a top neighboring region or a left neighboring region adjacent to a luma block corresponding to the chroma block;
• deriving down-sampled neighboring luma samples by down-sampling neighboring luma samples in the neighboring region;
• deriving a parameter for the inter-component reference of the chroma block based on the down-sampled neighboring luma samples;
• and
• predicting the chroma block based on the parameter for the inter-component reference,
• wherein deriving the parameter for the inter-component reference comprises:
• classifying the down-sampled neighboring luma samples into a first group and a second group, the first group including down-sampled neighboring luma samples having relatively large values and the second group including down-sampled neighboring luma samples having relatively small values;
• and
• calculating a maximum value by averaging the down-sampled neighboring luma samples included in the first group and a minimum value by averaging the down-sampled neighboring luma samples included in the second group,
• wherein the parameter for the inter-component reference is derived based on a difference between the maximum value and the minimum value,
• wherein when the top neighboring region belongs to a different coding tree unit from the luma block, only three neighboring luma samples are used to derive one down-sample neighboring luma sample, and
• wherein when the top neighboring region belongs to a same coding tree unit as the luma block, five or six neighboring luma samples are used to derive the one down-sample neighboring luma sample.