Displaying Images on a Color Graphic LCD

[Supercap2F]

Hey Guys!

I've been working on graphical stuff for LCDs recently, and right now I'm trying to display a image on a color TFT with a PIC. The driver chip for the display is a ILI9163, and the PIC is a 24EP512GP. The display is in a 5R:6G:5B 16 bit color format.

So my problem is turning a image into a C array of that format. From doing some research it looks like I can directly extract the image data from a 16-bit .bmp picture but I haven't been able to figure out how. I also found a couple programs that claimed they could make a C array from a image, but I haven't had luck with them either...

I really don't know if I'm going at this the right way or what to try next. So I thought I would see if I could get some tips here.

Thanks!!
Dan

 

[Harald Kapp]

This page gives links to two libraries ( Adafruit-GFX-Library and TFT_ILI9163C) which may help you. As far as I see these libs are for Atmel processors, but you may be able to adapt them to PICs.
Here's someone explaining a bit more detailed the usage of such an LCD.

This guy has a library which can (among others) convert an RGB24 value to an RGB565 value. A link to his github repository is at the bottom of the page.

The bmp file format for reading the bitmap into memory is described here.

 

[Supercap2F]

In your second link, the guy has a online program to convert a 24-bit .bmp file to 16-bit C array - which is just what I need. So I ran a bitmap through it and here's what I got on the display:

The original image (40x37px):


The code I used to display the array on the screen is:

for(y=0;y<40;y++)
        for(x=0;x<37;x++)
            PlotPoint(x,y,image[x+y*40]);

(which is paraphrased off his website)
I don't quite understand why I have to multiply x+y by 40 in the image variable, why couldn't I just put x+y in there (I tried it and it didn't work)? I must be doing something wrong given the output on the screen...

Thanks!!

P.S. How did you find the second link anyway? I googled for about an hour for something like this and didn't come up with anything really useful.

 

[Supercap2F]

I got it to work!

Apparently I had a issue with the way colors are transferred to the display with PlotPoint...

I also got rid of that weird strip at the bottom by changing the code:

for(y=0;y<37;y++)
        for(x=0;x<37;x++)
            PlotPoint(x,y,image[x+y*40]);

I still don't understand that x+y*40 thing though.

 

[Harald Kapp]

I don't quite understand why I have to multiply x+y by 40

image[] is a one dimensional array, where the data is arranged one line after the other. To get the index of a pixel in line y, row x, you have to find the starting index for this line within the array which is y*40 for a line length of 40, then index from that on to row x, so index=40*y +x.

How did you find the second link anyway? I googled for about an hour

I Googled too, for a few minutes. It's a matter of the right keywords. I used something like 'IL9163 library PIC' or similar. I don't remember exactly.

 

[Supercap2F]

Okay, That makes since. Thank you for your time Harald!

For anyone else reading this thread: I found a better image converter on github here. It's very nice and can import multiple file formats.
Dan