File > Open As Layers (or CTRL + ALT + O) will open a PDF with each page being a separate layer. After it has loaded, select the first page / layer and apply your filter of choice, then use the arrow keys to move down through the layers and CTRL + F to repeat the filter. Once done, just use File > Export As to export the file as a PDF and select the option to export layers as pages.
Not quite a batch run, but at two key presses per page it’s pretty quick.
Alternatively, the G’MIC-Qt (https://gmic.eu) package has:
Two functions that may help if you want to use the built in filters - one converts multiple layers into a single one (Layers to Tiles) and then another (Tiles to Layers) to convert it back again after you’ve applied your filter.
It also has other filters, such as “Clean Text” or “Repair Scanned Document” that you might find useful, and you can specify using the Input Layers dropdown (bottom-centre of the dialog) that you want to apply the selected filter to “All” layers.
File > Open As Layers (or CTRL + ALT + O) will open a PDF with each page being a separate layer. After it has loaded, select the first page / layer and apply your filter of choice, then use the arrow keys to move down through the layers and CTRL + F to repeat the filter. Once done, just use File > Export As to export the file as a PDF and select the option to export layers as pages.
Not quite a batch run, but at two key presses per page it’s pretty quick.
Alternatively, the G’MIC-Qt (https://gmic.eu) package has: Two functions that may help if you want to use the built in filters - one converts multiple layers into a single one (Layers to Tiles) and then another (Tiles to Layers) to convert it back again after you’ve applied your filter. It also has other filters, such as “Clean Text” or “Repair Scanned Document” that you might find useful, and you can specify using the Input Layers dropdown (bottom-centre of the dialog) that you want to apply the selected filter to “All” layers.