AVR Freaks

Is revalue, green value etc declared volatile?

I dare say the problem might be elsewhere. You also might want to consider using a better way of decoding the encoders. Using pcints is not the best way. As well, how are you managing debounce?

First off, this isn't correct, but not the main problem:

if ((PIND & (1<<PIND6)==0) && (PIND & (1<<PIND1)==7))

The ISR will run faster with four sets of if/else-if. You know RedValue++ and RedValue-- won't happen at the same time.

I see a big problem using a shared ISR. If an encoder is resting in its zero-zero position and another encoder is turning generating interrupts the resting channel will be incrementing.

The ISR tells you there was an edge, but not which of the eight inputs changed. You need a volatile variable that stores the value on PIND from the previous pass of the ISR. Then you can calculate which edge(s) occurred.

I think you have another serious problem when you start reading multiple encoders.  If encoder #1 changes and generates an interrupt, you will adjust e.g RedValue up or down.  But then if encoder #2 changes and generates an interrupt, you may adjust RedValue again, even though encoder #1 has not changed.  So I think you need to rethink your approach for multiple encoders (if I'm understanding things correctly).

Using your original code as an example,

ISR(PCINT2_vect)//Vector for Encoders
{
	if ((PIND & (1<<PIND0)==0) && (PIND & (1<<PIND1) == 0))
     	{
		 RedValue ++;
		}
    if ((PIND & (1<<PIND0)==0) && (PIND & (1<<PIND1) == 1))
		{
         RedValue --;
		}
......

Call the encoder connected to PIND0/PIND1 encoder #1.  Now suppose another encoder (2, 3 or 4) triggers an interrupt and this ISR runs.  Encoder #1 has not changed state, but RedValue will be incremented or decremented again if PIND0 is still at 0.

Well, if you can guarantee that two encoders won't be manipulated at the same time...

The AVR CPU executes at millions of instructions per second.  It can handle hundreds of encoders, "at the same time".

I recommend putting resistors and capacitors on the output pins of each encoder.  A pain at this point if the PCB has been laid out, true.  Next time don't lay out the PCB until the prototype works.

The R/C components will debounce your encoder signals and extend the pulses.  This is helpful when using cheap (<$1 per unit) encoders that generate very short pulses on turning.

Each of the four encoders will have an pin-change interrupt and a data pin:  8 input pins total.  Changing any encoder position will cause a pin-change interrupt.  In the IRQ, check the data line for the encoder to determine which direction that it was turned.   Have two boolean flags for the main code for each encoder.  One boolean flag indicates whether the individual encoder was changed and the other flag indicates its direction.   The main code polls the flags at least 20 times a second for movements on any of the four encoders.