问题
I would like to generate an image with to versions of the same fetch image, like this one:
Here are the two versions:
The background: https://res.cloudinary.com/nho/image/fetch/w_1024,h_512,c_thumb,g_auto,q_auto,f_auto/e_brightness:80/e_blur:3000/https://nicolas-hoizey.com/2016/08/a-bridge-not-so-far.jpg
The overlay: https://res.cloudinary.com/nho/image/fetch/w_1024,h_512,c_fit,q_auto,f_auto/https://nicolas-hoizey.com/2016/08/a-bridge-not-so-far.jpg
I don't understand how to do that with the documentation for overlays and for chained transformations.
回答1:
Cloudinary does not currently support using fetched images for overlay purposes.
If the source for these images (e.g. https://nicolas-hoizey.com) is known in advance then automatic-upload may be preferable.
Then, achieving the desired effect is done with the following transformation sequence: http://res.cloudinary.com/demo/image/upload/w_500/u_upload:2016:08:a-bridge-not-so-far,ar_2:1,c_scale,e_blur:2000,o_70,w_0.7,c_crop/h_1.0,fl_relative.layer_apply/2016/08/a-bridge-not-so-far.jpg
UPDATE: Cloudinary just announced a new support for overlaying dynamically fetched images. This is done by encoding the remote URL to Base64, e.g. (rails):
Base64.urlsafe_encode64("https://nicolas-hoizey.com/2016/08/a-bridge-not-so-far.jpg")
=> "aHR0cHM6Ly9uaWNvbGFzLWhvaXpleS5jb20vMjAxNi8wOC9hLWJyaWRnZS1ub3Qtc28tZmFyLmpwZw=="
Then the transformation URL will look something like: https://res.cloudinary.com/demo/image/fetch/w_500/u_fetch:aHR0cHM6Ly9uaWNvbGFzLWhvaXpleS5jb20vMjAxNi8wOC9hLWJyaWRnZS1ub3Qtc28tZmFyLmpwZw==,ar_2:1,c_scale,e_blur:2000,o_70,w_0.7,c_crop/h_1.0,fl_relative.layer_apply/https://nicolas-hoizey.com/2016/08/a-bridge-not-so-far.jpg
来源：https://stackoverflow.com/questions/39337286/overlay-a-fetched-image-over-itself-with-transformations-with-cloudinary