using loop to read in image files



I would like to read in a number of image files that are located in one folder using a loop. I used the "List Files" node followed by a "Table Row to Variable Loop Start". The output port of this node I connected then to the variable port of an "Image Reader" followed by the "Loop End" Node. However I dont get this thing to run. One problem is that the Image Reader always requires to select at least one file in the file browser window otherwise I get "Invalid Settings". If I do select a file and use under "Flow Variables" "Location" as the File name column it just reads in the one file (or whatever is selected ) multiple times.




Hi Christian,

try to connect the outport of the list files with the optional inport (actually just the only inport ;) ) of the Image Reader and configure the Image Reader as follows: "Advances Settings" select the correct column of the input table where the file names are stored, then the image reader shouldn't require a file anymore (at least I'm sure that it is like that in the latest nightly build of KNIME Image Processing). So you don't configure the Image Reader via Flow Variables (which is also an good idea actually), but you use the optional inport directly.

Does this help? If not, let me know, then I will provide you an example workflow.



Thank's Christian. It works great.


I'm trying to do the same but with cvs files. So i'm using a File Reader insted of Image Reader.  

Connect the outport of the list files with the inport refers to the red line? 

I the advanced setting I can't find something similar to the files names ...

Sorry, I'm new in Knime and i have problems looking for information. I tried to do the same via TableRow To Variable Loop, but always read the same file. The same problem as Christian at the begining.


The option you are looking for the File Reader is called DataURL which is the first one in the Flow Variables tab. Please note, the node need to have a valid configuration before the Flow Variable settings can be adjusted, simply select one example file with the same structure first.


Thank you very much. I selected in the DataURL "URL" and put "name" in the next space, also I have in the TableName "Knime.workspace". Actually is working, the problem is that I don't understand all these tricky, because I'm sure that I had tryed these options before. Do you know where to find documentation about these.

You are very kind and I appreciate a lot your support.


Most of those advanced concepts are covered by the KNIME Advanced User Training, that we run every other month in Zurich, see also for details. I would recommend browsing the forum and check out some of the workflows hosted on the Public Server.