Anyone with LED full color video screen experience

[maaze]

I have started a ledscreen project and find this thread very interesting. I have some question about gamma correction. The first is why the a ledscreen need it ? Is it for compensate for the nonlinjearity between the currrent and light output in the leds ? If that is the case can I use a static lockup table to convert my 8 bit value to 10 or 12 bits ? Thanks

 

[techie]

You are partially right. Gamma correction is to correct the LED current to eye sensation non-linearity. You can use a lookup table,

 

[maaze]

I have a question about my ledscreen project. Every ledmodule in my screen have 256 pixels and recive the pixel values from a serial link and store this in a buffer. Under the time a second buffer with the previous values drives the leds. But when will I switch to the new values ? First choise, every module switch to the new values when it have recived a new complete frame of values. The second choise, a command on the serial link switch to the new values on all modules on the same time after all modules have recived new values. The PWM frequence is 1kHz and the framespeed is 60 Hz. Thanks

 

[hm_fa_da]

Dear all

i am also designing a LED display using FPGAs and ...
but i don't have analog video signal , my controller reads bitmap data of each pixel from a digital memory ...

i don't know about gamma correction !!!
when i open a file in adobe photoshop , i can see a pixel each color data , for example : R = 100 , G = 50 , B = 220 .
i am saving these data for each pixel for each frame in a memory and then showing them on LED .
i am going to make 255 uS period for each line of LED , then for making R=100 , i turn on LED 100 us of 255 us and repeat it again ... ( 100 us on , 155 us off ) during this 255 us , G is on for 50 us and of the remained 205 us , B is on for 220 us and off the remained 25 us ...
is the way i am doing true ??? would i get the true color same as which is in Adobe photoshop ?
or i need to do some change ???