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@DichenZhang1 I tested this code, ```heif-enc 01_with_gain_map.jpg gm_01.heic```, but when open the gm_01.heic file in Mac, it seems not hava HDR effect as 01_with_gain_map.jpg. [01_with_gain_map.jpg.zip](https://github.com/user-attachments/files/20516973/01_with_gain_map.jpg.zip) Sincerely waiting for your reply...