Call Read to read data from the Blob field when the number of bytes in the field's data is not known. Buffer must have at least Count bytes allocated to hold the data that was read from the field.  

Read transfers up to Count bytes from the Blob data into Buffer, starting in the current position, and then advances the current position by the number of bytes actually transferred. Read returns the number of bytes actually transferred (which may be less than the number requested in Count.) 

Read checks the Transliterate property of the field, and converts the data into ANSI from the character set specified by the dataset if Transliterate is true. 

All the other data-reading methods of a Blob stream (ReadBuffer, ReadComponent) call Read to do their actual reading. 

Do not call Read when the TIBBlobStream was created in bmWrite mode.