Thermal Printer: printing graph image does not giving clear display

[Upol Ryskulova]

Hello,

I have printed graph image using thermal printer using Python-Thermal-Printer library. But graph did not displayed clearly( you should thinken your eye to the image :) ). System I am trying to implement is the real time system which plots two graphs simultanously while reading data. First I wanted to export that graph images as png or bmp after the all data received and then do printings. But after printing random graph image I see that it may not be a solution. What do you suggest? Or can I print two graphs through printer as the display is being displayed on a lcd screen?? Which approach will best suit? Could you please guide me?

Thank you very much.

Regards,

Upol 

[Upol Ryskulova]

Hello again, I want to update my question:

using thermal printer to print image containing two graphs (width is 384pixel wide as it is expected from the printer). Adafruit thermal printer link states that thermal printer can just print binary(monochrome) images. So I converted png image to bmp using zam-zam online vonverter. And used LCD Assitant software to get data values of the image. After this I run the python code to print the image as printertest.py did 

from PIL import Image
from Adafruit_Thermal import *
printer = Adafruit_Thermal("/dev/ttyO4", 19200, timeout=5)
import rot as result
printer.printBitmap(result.width, result.height, result.data)
printer.println("Adafruit!")
printer.feed(1)




But nothing got printed, excepts Adafruit line.

When I did print of png image converted to monochrome image by using PIL library, at least I was able to see unclear graph. How can I get clear graph prints from adafruit thermal printer? I really appreciate all your suggestions.

[Przemek Klosowski]

On Thu, Apr 9, 2015 at 10:53 AM, Upol Ryskulova <upol.ry...@gmail.com> wrote:

But nothing got printed, excepts Adafruit line.

When I did print of png image converted to monochrome image by using PIL library, at least I was able to see unclear graph. How can I get clear graph prints from adafruit thermal printer? I really appreciate all your suggestions.

Sorry but it's unlikely that you'll get an answer in this group. It just doesn't seem related to BBB. All I can say is that I'd try to get the printer to work in a configuration that they support, and dump the data directly going to the printer, using printf() statements, or wireshark or whatever. Then I'd set up the environment that doesn't work for you, and do the same thing, and compare the results. It could be different content, or different timing, or even a hardware error of some sort (loose connection etc).