Determining image orientation

Question

Creative Suite 3 (at least Photoshop and InDesign) now respect the <tiff:Orientation> value from the http://ns.adobe.com/tiff/1.0/ TIFF Properties namespace.<br /><br />This means that an image which has a tiff:Orientation of 1 is placed rotated by 90 degrees whereas an image with a tiff:Orientation of 0 is placed without rotation.<br /><br />Is it possible for a plug-in to determine whether the image has been rotated as a result of this XMP property?

Answer 1

Hi Nick,<br /><br />Yes it is possible for a plug-in to determine if an image has been rotated as a result of the tiff:Orientation tag. To do this you need to use the IImageAttributes interface of the kImageItem boss. The IImageAttributes interface is a collection of tags used to describe the attributes of a raster image. One of the tags contained in IImageAttributes is kPMTagMetaDataRotation. This tag holds the angle that was read out of the meta data tiff:orientation tag. I have pasted a code snippet below demonstrating how to retrieve the amount of rotation applied to the image.<br /><br />ErrorCode SnpGetImageAttributes::getAttributes(UIDList itemList)<br />{<br />  ErrorCode errorCode = kFailure;<br />  do {<br />    UIDList newList(itemList.GetDataBase()); <br /><br />    // Verify that the item selected is a graphic item.<br />    for (int32 i = 0; i < itemList.Length(); i++)<br />    {<br />      SnpGraphicHelper graphicHelper(itemList.GetRef(i));<br />      InterfacePtr<IImageDataAccess><br />        imageAccess(graphicHelper.QueryImageDataAccess());<br />      if (imageAccess)<br />     newList.Append( ::GetUID(imageAccess));<br />       }<br />      if (newList.Length() <= 0 ) <br />      {<br />     SNIPLOG("No item with graphics is selected.");<br />     break;<br />      }<br />     <br />      for (int32 i = 0; i < newList.Length(); i++)<br />      {<br />     // Get an interface pointer to the image attributes interface.<br />     InterfacePtr<IImageAttributes> <br />          iImageAttributes(newList.GetRef(i), UseDefaultIID()); <br />     if ( iImageAttributes ) <br />     { <br />       int32 width, height;<br />       int16 orientation; <br />          <br />       // Retrieve the heigh, width, and orientation<br />       // associated with the image and print them out.<br />       iImageAttributes->GetTag(IImageAttributes::kPMTagImageWidth, &width);              <br />         iImageAttributes->GetTag(IImageAttributes::kPMTagImageHeight, &height);<br />      iImageAttributes->GetTag(IImageAttributes::kPMTagMetaDataRotation, &orientation);<br /><br />       SNIPLOG("Width: %d", width);<br />       SNIPLOG("Height: %d", height);             <br />          SNIPLOG("Orientation: %d", orientation);<br />       SNIPLOG("==============================\n");<br />       errorCode = kSuccess;<br />     }<br />      }<br />    } while(false);<br />    return errorCode;<br />}<br /><br />Regards,<br /><br />DENVER