Generate N RGB tuples

generate_class_color.py

def generate_class_color(class_num=20):
    """Generate a RGB color set based on given class number.

    Args:
        class_num: Default is VOC dataset class number.

    Returns:
        A tuple containing RGB colors.
    """
    colors = [(1, 0, 1), (0, 0, 1), (0, 1, 1),
              (0, 1, 0), (1, 1, 0), (1, 0, 0)]
    const = 1234567  # only for offset calculation

    colorset = []
    for cls_i in range(class_num):
        offset = cls_i * const % class_num

        ratio = (float(offset) / class_num) * (len(colors) - 1)
        i = math.floor(ratio)
        j = math.ceil(ratio)
        ratio -= i

        rgb = []
        for ch_i in range(3):
            r = (1 - ratio) * colors[i][ch_i] + ratio * colors[j][ch_i]
            rgb.append(math.ceil(r * 255))
        colorset.append(tuple(rgb[::-1]))
    return tuple(colorset)