"""
Created on Thu Oct 21 11:09:09 2017
@author: Utku Ozbulak - github.com/utkuozbulak
"""
import os
import copy
import numpy as np
from PIL import Image, ImageFilter
import matplotlib.cm as mpl_color_map
import torch
from torch.autograd import Variable
from torchvision import models
def convert_to_grayscale(im_as_arr):
"""
Converts 3d image to grayscale
Args:
im_as_arr (numpy arr): RGB image with shape (D,W,H)
returns:
grayscale_im (numpy_arr): Grayscale image with shape (1,W,D)
"""
grayscale_im = np.sum(np.abs(im_as_arr), axis=0)
im_max = np.percentile(grayscale_im, 99)
im_min = np.min(grayscale_im)
grayscale_im = (np.clip((grayscale_im - im_min) / (im_max - im_min), 0, 1))
grayscale_im = np.expand_dims(grayscale_im, axis=0)
return grayscale_im
def save_gradient_images(gradient, file_name):
"""
Exports the original gradient image
Args:
gradient (np arr): Numpy array of the gradient with shape (3, 224, 224)
file_name (str): File name to be exported
"""
if not os.path.exists('../results'):
os.makedirs('../results')
# Normalize
gradient = gradient - gradient.min()
gradient /= gradient.max()
# Save image
path_to_file = os.path.join('../results', file_name + '.jpg')
save_image(gradient, path_to_file)
def save_class_activation_images(org_img, activation_map, file_name):
"""
Saves cam activation map and activation map on the original image
Args:
org_img (PIL img): Original image
activation_map (numpy arr): Activation map (grayscale) 0-255
file_name (str): File name of the exported image
"""
if not os.path.exists('../results'):
os.makedirs('../results')
# Grayscale activation map
heatmap, heatmap_on_image = apply_colormap_on_image(org_img, activation_map, 'hsv')
# Save colored heatmap
path_to_file = os.path.join('../results', file_name+'_Cam_Heatmap.png')
save_image(heatmap, path_to_file)
# Save heatmap on iamge
path_to_file = os.path.join('../results', file_name+'_Cam_On_Image.png')
save_image(heatmap_on_image, path_to_file)
# SAve grayscale heatmap
path_to_file = os.path.join('../results', file_name+'_Cam_Grayscale.png')
save_image(activation_map, path_to_file)
def apply_colormap_on_image(org_im, activation, colormap_name):
"""
Apply heatmap on image
Args:
org_img (PIL img): Original image
activation_map (numpy arr): Activation map (grayscale) 0-255
colormap_name (str): Name of the colormap
"""
# Get colormap
color_map = mpl_color_map.get_cmap(colormap_name)
no_trans_heatmap = color_map(activation)
# Change alpha channel in colormap to make sure original image is displayed
heatmap = copy.copy(no_trans_heatmap)
heatmap[:, :, 3] = 0.4
heatmap = Image.fromarray((heatmap*255).astype(np.uint8))
no_trans_heatmap = Image.fromarray((no_trans_heatmap*255).astype(np.uint8))
# Apply heatmap on iamge
heatmap_on_image = Image.new("RGBA", org_im.size)
heatmap_on_image = Image.alpha_composite(heatmap_on_image, org_im.convert('RGBA'))
heatmap_on_image = Image.alpha_composite(heatmap_on_image, heatmap)
return no_trans_heatmap, heatmap_on_image
def format_np_output(np_arr):
"""
This is a (kind of) bandaid fix to streamline saving procedure.
It converts all the outputs to the same format which is 3xWxH
with using sucecssive if clauses.
Args:
im_as_arr (Numpy array): Matrix of shape 1xWxH or WxH or 3xWxH
"""
# Phase/Case 1: The np arr only has 2 dimensions
# Result: Add a dimension at the beginning
if len(np_arr.shape) == 2:
np_arr = np.expand_dims(np_arr, axis=0)
# Phase/Case 2: Np arr has only 1 channel (assuming first dim is channel)
# Result: Repeat first channel and convert 1xWxH to 3xWxH
if np_arr.shape[0] == 1:
np_arr = np.repeat(np_arr, 3, axis=0)
# Phase/Case 3: Np arr is of shape 3xWxH
# Result: Convert it to WxHx3 in order to make it saveable by PIL
if np_arr.shape[0] == 3:
np_arr = np_arr.transpose(1, 2, 0)
# Phase/Case 4: NP arr is normalized between 0-1
# Result: Multiply with 255 and change type to make it saveable by PIL
if np.max(np_arr) <= 1:
np_arr = (np_arr*255).astype(np.uint8)
return np_arr
def save_image(im, path):
"""
Saves a numpy matrix or PIL image as an image
Args:
im_as_arr (Numpy array): Matrix of shape DxWxH
path (str): Path to the image
"""
if isinstance(im, (np.ndarray, np.generic)):
im = format_np_output(im)
im = Image.fromarray(im)
im.save(path)
def preprocess_image(pil_im, resize_im=True):
"""
Processes image for CNNs
Args:
PIL_img (PIL_img): PIL Image or numpy array to process
resize_im (bool): Resize to 224 or not
returns:
im_as_var (torch variable): Variable that contains processed float tensor
"""
# mean and std list for channels (Imagenet)
mean = [0.485, 0.456, 0.406]
std = [0.229, 0.224, 0.225]
#ensure or transform incoming image to PIL image
if type(pil_im) != Image.Image:
try:
pil_im = Image.fromarray(pil_im)
except Exception as e:
print("could not transform PIL_img to a PIL Image object. Please check input.")
# Resize image
if resize_im:
pil_im = pil_im.resize((224, 224), Image.ANTIALIAS)
im_as_arr = np.float32(pil_im)
im_as_arr = im_as_arr.transpose(2, 0, 1) # Convert array to D,W,H
# Normalize the channels
for channel, _ in enumerate(im_as_arr):
im_as_arr[channel] /= 255
im_as_arr[channel] -= mean[channel]
im_as_arr[channel] /= std[channel]
# Convert to float tensor
im_as_ten = torch.from_numpy(im_as_arr).float()
# Add one more channel to the beginning. Tensor shape = 1,3,224,224
im_as_ten.unsqueeze_(0)
# Convert to Pytorch variable
im_as_var = Variable(im_as_ten, requires_grad=True)
return im_as_var
def recreate_image(im_as_var):
"""
Recreates images from a torch variable, sort of reverse preprocessing
Args:
im_as_var (torch variable): Image to recreate
returns:
recreated_im (numpy arr): Recreated image in array
"""
reverse_mean = [-0.485, -0.456, -0.406]
reverse_std = [1/0.229, 1/0.224, 1/0.225]
recreated_im = copy.copy(im_as_var.data.numpy()[0])
for c in range(3):
recreated_im[c] /= reverse_std[c]
recreated_im[c] -= reverse_mean[c]
recreated_im[recreated_im > 1] = 1
recreated_im[recreated_im < 0] = 0
recreated_im = np.round(recreated_im * 255)
recreated_im = np.uint8(recreated_im).transpose(1, 2, 0)
return recreated_im
def get_positive_negative_saliency(gradient):
"""
Generates positive and negative saliency maps based on the gradient
Args:
gradient (numpy arr): Gradient of the operation to visualize
returns:
pos_saliency ( )
"""
pos_saliency = (np.maximum(0, gradient) / gradient.max())
neg_saliency = (np.maximum(0, -gradient) / -gradient.min())
return pos_saliency, neg_saliency
def get_example_params(example_index):
"""
Gets used variables for almost all visualizations, like the image, model etc.
Args:
example_index (int): Image id to use from examples
returns:
original_image (numpy arr): Original image read from the file
prep_img (numpy_arr): Processed image
target_class (int): Target class for the image
file_name_to_export (string): File name to export the visualizations
pretrained_model(Pytorch model): Model to use for the operations
"""
# Pick one of the examples
example_list = (('../input_images/snake.jpg', 56),
('../input_images/cat_dog.png', 243),
('../input_images/spider.png', 72))
img_path = example_list[example_index][0]
target_class = example_list[example_index][1]
file_name_to_export = img_path[img_path.rfind('/')+1:img_path.rfind('.')]
# Read image
original_image = Image.open(img_path).convert('RGB')
# Process image
prep_img = preprocess_image(original_image)
# Define model
pretrained_model = models.alexnet(pretrained=True)
return (original_image,
prep_img,
target_class,
file_name_to_export,
pretrained_model)
