I need to resize and crop an image to a specific width and height. I was able to construct a method that will create a square thumbnail, but I'm unsure on how to apply this, when the desired thumbnail is not square.
def rescale(data, width, height):
"""Rescale the given image, optionally cropping it to make sure the result image has the specified width and height."""
from google.appengine.api import images
new_width = width
new_height = height
img = images.Image(data)
org_width, org_height = img.width, img.height
# We must determine if the image is portrait or landscape
# Landscape
if org_width > org_height:
# With the Landscape image we want the crop to be centered. We must find the
# height to width ratio of the image and Convert the denominater to a float
# so that ratio will be a decemal point. The ratio is the percentage of the image
# that will remain.
ratio = org_height / float(org_width)
# To find the percentage of the image that will be removed we subtract the ratio
# from 1 By dividing this number by 2 we find the percentage that should be
# removed from each side this is also our left_x coordinate
left_x = (1- ratio) / 2
# By subtract the left_x from 1 we find the right_x coordinate
right_x = 1 - left_x
# crop(image_data, left_x, top_y, right_x, bottom_y), output_encoding=images.PNG)
img.crop(left_x, 0.0, right_x, 1.0)
# resize(image_data, width=0, height=0, output_encoding=images.PNG)
img.resize(height=height)
# Portrait
elif org_width < org_height:
ratio = org_width / float(org_height)
# crop(image_data, left_x, top_y, right_x, bottom_y), output_encoding=images.PNG)
img.crop(0.0, 0.0, 1.0, ratio)
# resize(image_data, width=0, height=0, output_encoding=images.PNG)
img.resize(width=witdh)
thumbnail = img.execute_transforms()
return thumbnail
If there is a better way to do this please let me know. Any help would be greatly appreciated.
Here's a diagram explaining the desired process.
Thanks,
Kyle
To set a custom crop ratio, tap on the preset dimensions at the top of your screen. Adjust the width and height of your custom crop ratio and adjust to get to your ideal dimensions. Select OK to apply your changes.
Resize your images to fill specified dimensions by setting the width and height (w and h in URLs), while setting the crop parameter to fill (c_fill in URLs). This will resize and crop the image so an image with the exact specified dimensions is generated.
I had a similar problem (your screenshot was very useful). This is my solution:
def rescale(img_data, width, height, halign='middle', valign='middle'):
"""Resize then optionally crop a given image.
Attributes:
img_data: The image data
width: The desired width
height: The desired height
halign: Acts like photoshop's 'Canvas Size' function, horizontally
aligning the crop to left, middle or right
valign: Verticallly aligns the crop to top, middle or bottom
"""
image = images.Image(img_data)
desired_wh_ratio = float(width) / float(height)
wh_ratio = float(image.width) / float(image.height)
if desired_wh_ratio > wh_ratio:
# resize to width, then crop to height
image.resize(width=width)
image.execute_transforms()
trim_y = (float(image.height - height) / 2) / image.height
if valign == 'top':
image.crop(0.0, 0.0, 1.0, 1 - (2 * trim_y))
elif valign == 'bottom':
image.crop(0.0, (2 * trim_y), 1.0, 1.0)
else:
image.crop(0.0, trim_y, 1.0, 1 - trim_y)
else:
# resize to height, then crop to width
image.resize(height=height)
image.execute_transforms()
trim_x = (float(image.width - width) / 2) / image.width
if halign == 'left':
image.crop(0.0, 0.0, 1 - (2 * trim_x), 1.0)
elif halign == 'right':
image.crop((2 * trim_x), 0.0, 1.0, 1.0)
else:
image.crop(trim_x, 0.0, 1 - trim_x, 1.0)
return image.execute_transforms()
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With