SumatraPDF can open folders of images
IF the sub-folder is dropped onto the session window OR a shortcut
SumatraPDF has no built in color controls to adjust “contrast” or color balance it is expected that the images are already optimized by the author for viewing.
You can change the images externally with an image editor whilst viewing them. https://en.wikipedia.org/wiki/ImageMagick has countless ways of adjusting image colour ranges so you could test them sequentially whilst watching the results in SumatraPDF.
As with any external editor if each image file is under 10 Mb in formal release or 32 Mb in pre-release they are not locked and any saved changes appear “real time” within SumatraPDF.
There is a limitation to dropping folders that you may find relevant. If you wish to send the images “one by one” from SumatraPDF to an editor then you must open the group of files by dragging groups (or file open and selecting all files of interest) then they will become separate tabs.
Each tab can be reviewed and that tabs image can be sent with a command like this
If you are creative you could just store the image names to be auto corrected in a list then later batch process that list using command line to perform corrections e.g. IrfanView has a parameter “/filelist=” other editors have similar arguments.
When finished with your changes SumatraPDF can save a sub-folders contents as a PDF or simpler right click the sub-folder files to combine in explorer as .zip and rename that to .cbz which is easier to save as PDF.
With the new experimental pre-release dailybuilds bookmark functions you can save a .bkm in the folder above that sub-folder. At present that function would not be of much benefit except to cusomise the filenames whilst viewing.
More useful still you can right-click and save as NewBookmarks.vbkm and add those together so that a few folders or cbr can be stored in one collection.vbkm
Now when you open that .vbkm then all the images are in the bookmarks list
As you read the images you can EDIT entries to show “à la volée” a bold or italic marker so you can see the last position or items of interest, and even add color text to the bookmark