I can't make out a lot of the information. Do I try to index what I can make out as best guess or do I need to report it as "no extractable data".
The thought of not being able to index this information makes my heart hurt.
In addition to inverting the image and fiddling with the brightness and contrast, etc., I tried several different sharpening techniques that I have (A Viewer For Windows, Smart Deblur, Blur Fix, InPixio PhotoFocus), with no tangible improvement. I think you need to do your best to index what you can make out.
You are correct in your feelings, we don't want to lose any information if we can possibly make it out. I believe our instructions are
#1- Don't mark it as "no extractable data" as there is information that can be read.
#2- If you don't feel comfortable trying the batch return it and someone else will try.
#3- If you can do your best using ? or * to mark unreadable letters or groups of letters as discussed in the general guidelines. I find that overlaying the ruler onto what I am trying to make out sometimes makes it easier to read. I looked at the batch and changing the brightness and contrast didn't help much for me. John Empoliti has some good ideas on how to improve the image if he sees this post he might be able to help.
keep up the good work, hope this helps