Raster Image Functions:
 Input and Output
  Maintaining File Comments and Tags

For the comment to be saved:

L_GetComment

L_SetComment

L_WriteFileComment

For the comment in an existing file:

L_ReadFileComment

L_ReadFileCommentMemory

L_ReadFileCommentOffset

L_WriteFileCommentExt

For the TIFF tag to be saved:

L_GetTag

L_SetTag

L_WriteFileTag

For the TIFF tag in an existing file:

L_EnumFileTags

L_ReadFileTag

L_ReadFileTagMemory

L_WriteFileTag

For the FlashPix Comments:

L_GetFileCommentSize

L_ReadFileComment

L_ReadFileCommentExt

L_SetComment

L_WriteFileCommentExt