Convert a rectangular region to a Picture object.
convertRegionToPicture2([in] int page, [in] int regionX, [in] int regionY, [in] int regionW, [in] int regionH, [in] double hDPI, [in] double vDPI, [in] int color, [out, retval] IUnknown **pic)
This function converts a rectangular region of a PDF page to a Picture object (OLE IPicture interface). It is identical to convertRegionToPicture, except that it allows the horizontal and vertical resolutions to be controlled independently.

The rectangular region is specified by the x,y coordinates of its upper-left corner and its width and height - in bitmap coordinates, not PDF coordinates. That is, if the whole-page bitmap would have been 1000 pixels wide and 2000 pixels high, and you request a region with (x,y) = (0,0) and (w,h) = (1000,500), the resulting bitmap will be the top fourth of the page.

The arguments are:

Note that the color settings are read-only properties on the COM component, so you'll need to use pdf.imageMono, etc.

The imageDevNToRGB mode produces RGB output like imageRGB, but does the rasterization in DeviceN (CMYK + spot colors) so overprint previews will be more accurate.

The imageGrayToMono mode does the rasterization in 8-bit grayscale and converts to 1-bit monochrome at the end. This is useful for files that use transparency – because 1-bit monochrome mode doesn't support transparency.

' convert the top part of page 5 to a 144x72 dpi color Picture object picBox.Picture = pdf.convertRegionToPicture2(5, 0, 0, 1000, 500, 144, 72, pdf.imageRGB)