OP_TIFEDIT: Edit TIFF Tags and File Contents

The purpose of OP_TIFEDIT is to assemble a common set of TIFF file tag editing and contents editing routines into a simple low level interface scheme for general availability. The requirement to insert, replace, delete, and edit TIFF tags in any of a TIFF file's pages along with the ability to insert, extract, replace, and delete any page in a TIFF file are common requirements in many imaging systems.

The TIFF_EDIT:OP_TIFEDIT section of PIC_PARM describes the details of the structure tused to control OP_TIFEDIT's actions. The following table outlines the current feature set of OP_TIFEDIT.

Delete a TIFF IFD Page

• The Put Queue contains the TIFF file with the page to be deleted.
• Put_Page is set to the page (IFD) number to be deleted.
• The NumPages contains the number of consecutive pages to deleted. For backward compatibility, a NumPages of 0 is treated the same as a 1.

The deleted pages do not compact the Tiff file with this operation. If the requested pages do not exist, an error is returned.

Insert a TIFF IFD Page

• The Get Queue contains the TIFF page to be inserted.
• The source page is set in Get_Page.
• The number of consecutive source pages is set in NumPages.
• The Put Queue contains the TIFF file to receive the new page.
• The inserted page will be inserted before the page set in Put_Page.

The destination Tiff file will increase by the size of the inserted pages. If one of the source pages does not exist, an error is returned. If the designated destination Page does not exist, the inserted page will be appended to the end of the destination Tiff File

Replace a TIFF IFD Page

• The Get Queue contains the TIFF source page.
• The Put Queue contains the TIFF file to receive the new page.
• Put_Page specifies the destination IFD page to be replaced.

The destination Tiff file will increase by the size of the inserted page. If either the source or destination page do not exist an error is returned.

Extract a TIFF IFD Page

• The Get Queue contains the TIFF source file.
• The Put Queue receives the requested page as a stand-alone TIFF image file.
• Get_Page specifies which IFD page to extract.

The Put queue will contain the desired page as a single page TIFF file.

Compact TIFF File

• The Get Queue contains the TIFF source file.
• The Put Queue receives the TIF image with all unused space from other TIFF edit operations discarded.

The Tiff source stream will be read from the Get Queue and placed in the Put Queue discarding wasted unused space acquired from the other Tiff Edit operations.

Acquire, Edit, and Set the Tiff Tags

• The Get Queue contains the TIFF source file.
• The Put Queue receives the modified TIF image with all IFD edits applied.
• Get_Page is set to the page to receive the edits.

The Tiff source file will be read from the Get Queue upon the REQ_INIT request cycle and a PIC2List will be retuned on the corresponding (first) RES_DONE  response. The user edits, adds, and deletes the Tiff Tag list as desired prior to REQ_EXEC phase.  When the REQ_EXEC phase is executed, the PIC2List is added appropriately to the output Put Queue stream. The Tags read and written will belong to the specified IFD page in Get_Page. The tags (actually the IFD) will be added to the end of the Put Queue stream, hence enlarging the Tiff stream. This command is a bit tricky that the input file should be opened for read and the same file (or a copy) opened for read/write. The read only file is in the get queue and the read/write file in the put queue.

The following Tags cannot be viewed or changed:

TAG_StripByteCounts:

            TAG_StripOffsets:

            TAG_JPEGProc:

            TAG_JPEGInterchangeFormat:

            TAG_JPEGInterchangeFormatLength:

            TAG_JPEGRestartInterval:

            TAG_JPEGLosslessPredictors:

            TAG_JPEGPointTransforms:

            TAG_JPEGQTables:

            TAG_JPEGDCTables:

            TAG_JPEGACTables:

The following Tags can be viewed but not changed:

            TAG_RowsPerStrip:

            TAG_SamplesPerPixel:

            TAG_ImageWidth:

            TAG_ImageLength:

            TAG_Compression:

            TAG_T4Options:

            TAG_T6Options:

            TAG_YCbCrSubSampling:

            TAG_BitsPerSample:

            TAG_PhotometricInterpretation:

Limitations:

Tiled Tiff files will not be supported at this time.