matplotlib 更改 jpg 图像颜色

问题描述

我正在使用 matplotlib imread 函数从文件系统读取图像.但是，当显示这些图像时，它将更改jpg图像的颜色.[Python 3.5，Anaconda3 4.3，matplotlib2.0]

I'm reading images from filesystem using matplotlib imread function. However, it changes jpg image color when it displays those images. [Python 3.5, Anaconda3 4.3, matplotlib2.0]

# reading 5 color images of size 32x32
imgs_path = 'test_images'
test_imgs = np.empty((5,32,32,3), dtype=float)
img_names = os.listdir('test_images'+'/')
for i, img_name in enumerate(img_names):
    #reading in an image
    image = mpimg.imread(imgs_path+'/'+img_name)
    test_imgs[i] = image

#Visualize new raw images
plt.figure(figsize=(12, 7.5))
for i in range(5):
    plt.subplot(11, 4, i+1)
    plt.imshow(test_imgs[i])
    plt.title(i)
    plt.axis('off')
plt.show()

它将为所有图像添加蓝色/绿色调.我在做任何错误吗?

It is adding a bluish/greenish tint to all the images. Any mistake I'm doing?

推荐答案

matplotlib.image.imread 或 matplotlib.pyplot.imread 将图像读取为无符号整数数组.
然后，您将其隐式转换为 float .

matplotlib.image.imread or matplotlib.pyplot.imread read the image as unsigned integer array.
You then implicitely convert it to float.

matplotlib.pyplot.imshow 以不同的方式解释两种格式的数组.

matplotlib.pyplot.imshow interpretes arrays in both formats differently.

• 浮点数组在 0.0 (无颜色)和 1.0 (全色)之间解释.
• 整数数组在 0 和 255 之间解释.

• float arrays are interpreted between 0.0 (no color) and 1.0 (full color).
• integer arrays are interpreted between 0 and 255.

因此您有两个选择:

1. 使用整数数组

1. Use an integer array

test_imgs = np.empty((5,32,32,3), dtype=np.uint8)

在绘制之前将数组除以 255:

divide the array by 255. prior to plotting:

test_imgs = test_imgs/255.

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