How to convert a png file to .GRF file used for zebra printer

Question

I use Zebraprinter for printing the labels. My printer is 203dpi. For last couple of days i was searching in internet and i found there are Zebraprint utilities.. to convert to DFR format.. which sucks.. they are not fully explaining how to do this.. They just says convert to ~DG format. any print it, which is not happening!! Rather I would like to convert a png file to a .GRF file and send to the printer for printing.. IS there any deadly available free software in internet which does my needs, Also, i tired to develop a software which does the job for printing the letters.. which is wiring fine. i don't know how to print pictures using this printer. I need to convert this image https://imageshack.com/i/pb0BArbep to .GRF format. How can i do all this under a single button press.. Any helps..

Thanks a lot.

Code snippet:-

private void button2_Click(object sender, EventArgs e)
    {
        string s = Print();
        PrintFactory.sendTextToLPT1(s);
    }

 private string Print()
    {
        string s = "";
        s += "^XA^LH"+ text.textbox + ".GRF,1,1^FS";

        s += "^FO250,294^FD^FS";
        s += "^XZ";
        return s;
    }

Answer 1

It's been a month since this was asked, so I don't know if an answer is still needed or not, but I'll have a go at it. I've actually been doing a lot of research on ZPL lately, (one of the reasons I came across this question), and I had to do something similar. With a 203 dpi printer as well, actually. I'm not sure how to convert a PNG to GRF, but I was able to print out a graphic using just a PNG:

^XA
^MNY
^LL203
~DYE:{name},P,P,{file size},,{data}
^XZ

The ^MN has to do with Media Tracking, and you may have to change it a bit to suit your needs, depending on the label. Same thing with ^LL, which specifies the label length. For an 8 dots/mm (203 dpi), the value you use as an argument is calculated by 203.2 * length of label in inches. After that, there's a few values to plug into ~DY (Download graphics, page 112 on the manual), the first of which is the name you want to use to reference the file. I didn't add a file extension, as the printer seemed to do that for me, since I specified it was a PNG in the arguments. The second is the size, in bytes, of the PNG file. And lastly, the actual data from the file in the form of ASCII hex. Now with the file being saved on the printer, I was then able to print the graphic in a script using:

^IME:{name}.PNG
^FS

Note: After uploading the file to the printer, I was able to confirm it did save as a PNG file by connecting to the printer VIA IP in a browser and going to "Directory Listing". I'm not sure if all those printers have this feature, but the one I used did. If it does, you can use this to confirm that the file properly uploaded. (It should be in Onboard Flash)

Hope this helps!

The manual I used is here. I also came across numerous other StackOverflow questions that helped out a bit, and a few threads on other forums. One question that was also in C# that helped me quite a bit can be found here.