IV-3A/IV-6 VFD Clock LDR sensor working "backwards"

Hello everyone!

This is my first post on this forum, but I joined and follow it for some time.
So far I have built four nixie clocks, all of them are based on Classic Rev6 Clock by Ian Sparkes, and all of them are working perfectly (3 years now!).
I do like the software on them clocks, there is so many options and they can be easily changed via wifi.
So, for a change, my current project is based on IV-3A/IV-6 VFD Clock by Ian as well.
I know this is still not finished project, but I decided to build it anyway, and it works mostly fine.
Here is the link to the firmware: ESP8266 VFD Clock

But there is a problem with LDR sensor, it works, but the other way around, meaning when its dark the tubes are in full brightness, and in full light they are dimmed.
I think it is a software problem, but unfortunately my programming skills are very limited, and this firmware is way too complicated for me.
Any idea how to fix this? Tbh, I am hoping for Ian to answer this, because he is an author, but any help and insights is appreciated.

Thanks in advance,
Lukas

Hi Ian,
Actually I am not using any of them. I made the pcb myself (oldskool toner transfer metod:), because I am using IV-11 tubes, four of them. Also I replaced optocouplers with two UDN2981LW drivers. When I stated the clock first time it was showing some gibberish, but then I found that in the code there is an option to change the 74hc595 outputs from inverted to normal, and after I did that, the clock started to work ok. I can upload some pictures later, when I come back from work.

Thanks, Lukas

Ok, here are some pictures:

First one with LDR sensor in full light, second with LDR covered with some shrinking tube. You can see LDR value and digit brightness on the screen behind.
Few more things:
-all connections are according to the schematic, so one end of LDR goes to VCC and another one goes to pin A0 of Wemos,
-I am not using LED backlights, because I prefer natural look of them tubes,
-l am using firmware from the link in my first post, the only change I made is this:
#define INVERT_595_OUTPUTS // INVERT_595_OUTPUTS | NORMAL_595_OUTPUTS
changed it to:
#define NORMAL_595_OUTPUTS // INVERT_595_OUTPUTS | NORMAL_595_OUTPUTS

I have tried to alter the formula in line 2552 of the code:
float digitBrightness = ldrManager.getLDRValue() * 100.0 / (float) COUNTS_PER_DIGIT;
but i discovered, that it is only responsible for value of brightness displayed on the website and it does not affect the actual tube brightness.
Then I tried to make some changes in LDRManager.cpp file, but did not succeed. Too advanced for me, can't decode the Matrix

thanks, Lukas

Of course! You are right!
It works fine now!
Oh, silly me, how did I miss that? I thought that R15 (10k) on the schematic actually IS LDR!
Well, problem solved, thank you very much!

thanks, Lukas