Image Writer Help

Hi, I have a table output like the one above. I am trying to create JPG files from the third column while naming the images with the first column. This is my first time doing image processing in KNIME.

I tried to use the Image Writer (Table) since I have multiple images, but it asks for “ImageValue”. What does that mean? I then tried the Image Writer, it works out okay, but I’m not able to pick the first column as the filename column without the directory box being disabled.

Please help. Thanks in advance!

Hi @badger101

I just tried the -Image Writer (Table)- node and it didn’t ask me for a “Image Value”. Maybe I’m missing something :thinking: ?

These are the fields I have filled and it worked:

Could you lease upload the table of your snapshot in a minimalist workflow to try to help you further from there ?

Hope it helps.

Thanks & regards,


@badger101, @aworker this workflow would demonstrate how to list a bunch of PNG files and then give them a new name and save them to another folder.

You might want to download the whole workflow group. It’s from a german introduction into KNIME but I think the functions should be clear:

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@aworker Hi, this is the truncated version of my workflow. I exported with errors.
KNIME_Image.knwf (155.2 KB)

@mlauber71 Hello, thanks for uploading the output image of your String Manipulation Node. After seeing that, and relooking at my Image Writer Node, I realized I had to append the absolute path. And I also had to add a unique character such as the row index for filenames that are similar to distinguish them from one another. I am now able to create all 300+ images from my table.

I’m still curious though, why I can’t use the Image Writer Table as it’s asking me for the Column Values. Maybe it only works with images like yours which are charts containing numerical figures?

Hi @badger101

I believe the problem comes from the fact that the images are in an internal KNIME format called ImgPlus which is not compatible with the -Image Writer- node you were trying.

Please try this other one -Image Writer- from the “KNIME Image Processing” plugin which seems to be compatible:

and provided the following results for your images

I just remembered that this other solution is possible too :thinking:

Convert the ImgPlus image into a PNG image :wink:

Once the images are of type PNG, you could add @mlauber71’s solution to deal from there with images that are not of type ImgPlus and save them with proper names.

Hope it helps.



Thanks a lot @aworker !

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@badger101 my pleasure :wink: !

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