Generate jpg files using line length (pixels) and orientation (degrees)

Denis McMahon denismfmcmahon at gmail.com
Fri Jan 9 03:54:00 CET 2015


On Thu, 08 Jan 2015 22:07:03 +0000, Denis McMahon wrote:

> On Thu, 08 Jan 2015 09:09:18 -0800, semeon.risom wrote:
> 
>> Simple question. I hope. .....

To follow up, below is a solution to the problem you stated.

#!/usr/bin/python

import Image, ImageDraw, math

def makeimg(length, orientation):
    """
    Make an image file of a black 4 pixel wide line of defined length 
    crossing and centered on a white background of 800 px square, save
    as a png file identifying line length and orientation in the file 
    name.
    param length - pixels, length of the line
    param orientation - degrees, orientation ccw of the line from +ve x 
    axis
    Files are saved in imgs subdir, this must already exist.
    File name is image_lll_ooo.jpg
    lll = length, ooo = orientation, both 0 padded to 3 digits
    """

    # check length is +ve and not greater than 800
    if length < 0:
        length = length * -1
    if length > 800:
        length = 800

    # check orientation is positive in range 0 .. 179
    while orientation < 0:
        orientation = orientation + 360
    if orientation > 179:
        orientation = orientation % 180

    # calculate radius in pixels and orientation in radians
    radius = length / 2
    orient = math.radians(orientation)

    # calculate xy coords in image space of line end points
    x1 = int(400 + (radius * math.cos(orient)))
    y1 = int(400 - (radius * math.sin(orient)))
    x2 = int(400 + (-radius * math.cos(orient)))
    y2 = int(400 - (-radius * math.sin(orient)))

    # create an image
    img = Image.new('RGB', (800,800), 'rgb(255, 255, 255)')
    # create a draw interface
    draw = ImageDraw.Draw(img)

    # draw the line on the image
    draw.line([(x1, y1), (x2, y2)], fill='rgb(0, 0, 0)', width=4)

    # determine file name, save image file
    fn = 'imgs/image_{:03d}_{:03d}.jpg'.format(length,orientation)
    img.save(fn)

# stepping through ranges of values
for length in range(100, 601, 100):
    for orientation in range(0, 171, 10):
        makeimg(length, orientation)

# using lists of values
for length in [50, 150, 250, 350, 450, 550, 650]:
    for orientation in [0, 15, 40, 45, 60, 75, 90, 105, 120, 135, 150, 
165]:
        makeimg(length, orientation)




-- 
Denis McMahon, denismfmcmahon at gmail.com



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