BIRT - PDF Report Image Quality

Hey folks,

I created a BIRT report and want to export this report as a PDF file, in which I want to include two images (BMP, 1001 x 1001 pixels). The problem is, that the image quality within the PDF file is very poor. And no matter what I try, I cannot make them look good.

The images come into BIRT via a Data to Report node with the Export Images as PNG option selected. Changing the option to SVG does not change the result.

Within BIRT I played around with the Image DPI option, of course, no improvements here.

When opening the PDF file in Adobe Acrobat Pro I can see, that the image stored within the file is only 195 x 195 pixels in size.

Help is very much appreciated!



The images have the same size (resolution) as the thumbnails in the corresponding table. So maybe it's not a BIRT problem?


When using custom image scaling in the Data to Report node, the image is not scaled as one would think. Instead it is expanded with white pixels.



When manually adding a pic to BIRT ("embedded image") everything is fine.


When changing the image cell height option of the Image Processing Plugin, it directly affects the image output size within BIRT. Makes absolutely no sense to me and is super inconvenient, but will act as a workaround for my reports.

Hi Marc,

actually, this is more or less intended behaviour, however, it's not too obvious, so let me try to explain what is happening.  Everything should work as expected with standard KNIME Image Cells (not KNIME Image Processing Plugin). Cells created using e.g. the Image Reader in KNIME Image Processing are potentially multi-dimensional images stemming from an arbitrary format. In order to bring them into the report, KNIME simply takes the thumbnail renderer of KNIME Image Processing and "draws" the images into the report. Therefore, the size of the image 1-to-1 corresponds to the thumbail renderer size and _not_  to the size of the actually underlying image.

A workaround would be to manually convert the ImgPlusValues to PNG Images using the corresponding node in KNIME Image Processing. Then you have full-sized PNG images.

I hope this makes more sense now. Sorry for the trouble!



Hey Christian,

now it makes more sense and I know how to handle it in the future. So, thank you for your answer!