How do I convert a csv file (16bit (high) color) to image in Python?

Question

Context: I built a small thermal camera which can save 70x70 pixels to an SD card. These pixels have a color value ranging from 0 to 2^16. (Actually certain colors, like black (value 0) are never displayed). This color is determined like explained here: c++ defined 16bit (high) color

I want to convert this data into an Image with my computer using Python.

An example gathered from another question unfortunately doesn't yield satisfying results: bad image

As you can see, the image doesn't look very good. My screen shows something like this (note that these two examples were not captured at the same time): photo

The white frame is not part of the csv-file.

This is the code I have used to generate the image: I have experimented with the color_max value but didn't get good results.

#Python CSV to Image converter
#pip2 install cImage
#pip2 install numpy

from PIL import Image, ImageDraw
from numpy import genfromtxt

color_max = 256
#original 256

g = open('IMAGE_25.TXT','r')
temp = genfromtxt(g, delimiter = ',')
im = Image.fromarray(temp).convert('RGB')
pix = im.load()
rows, cols = im.size
for x in range(cols):
    for y in range(rows):
        #print str(x) + " " + str(y)
        pix[x,y] = (int(temp[y,x] // color_max // color_max % color_max),int(temp[y,x] // color_max  % color_max),int(temp[y,x] % color_max))
im.save(g.name[0:-4] + '.jpeg')

This is the csv-file: Image Data

31 represents blue in this case, high values are more red.

Thanks for any help!

Here's some additional information about my project:

Arduino Thermal Camera with SD card support and image saving capability using the AMG8833 Thermal Imaging sensor made by Panasonic: Datasheet

GitHub (Arduino and Python Code)

3D-printable case used by me and original Arduino code

Schematic with SD card added

If you feel like adding the make and model of your camera to your question (click edit just above this comment) that may help other folk find it. — Mark Setchell
– Mark Setchell, Commented Aug 27, 2018 at 20:52

Zoe - Save the data dump · Accepted Answer · 2022-12-26 11:10:56Z

3

I think it should look like this:

#!/usr/local/bin/python3
import numpy as np
from PIL import Image

# Read 16-bit RGB565 image into array of uint16
with open('IMAGE_25.TXT','r') as f:
    rgb565array = np.genfromtxt(f, delimiter = ',').astype(np.uint16)

# Pick up image dimensions
h, w = rgb565array.shape

# Make a numpy array of matching shape, but allowing for 8-bit/channel for R, G and B
rgb888array = np.zeros([h,w,3], dtype=np.uint8)

for row in range(h):
    for col in range(w):
        # Pick up rgb565 value and split into rgb888
        rgb565 = rgb565array[row,col]
        r = ((rgb565 >> 11 ) & 0x1f ) << 3
        g = ((rgb565 >> 5  ) & 0x3f ) << 2
        b = ((rgb565       ) & 0x1f ) << 3
        # Populate result array
        rgb888array[row,col]=r,g,b

# Save result as PNG
Image.fromarray(rgb888array).save('result.png')

edited Dec 26, 2022 at 11:10

Zoe - Save the data dump

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answered Aug 27, 2018 at 6:12

Mark Setchell

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2 Comments

Wi_Zeus Over a year ago

This was exactly what I was looking for! Thanks a lot. I hope that this answer will help others too.

Mark Setchell Over a year ago

Cool - glad to be of assistance. Good luck with your project!

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