Magento 2 - Why is product image size & dimensions changed after upload?

Question

When uploading new images to a product in Magento 2, it is not only decreasing the dimensions of the image, but it's increasing the image file size:

Image Details Before Upload

• Dimensions: 1185 × 1580 px
• File Size: 446 KB

After Upload

Can anybody explain why this is happening? I accept that some data may be added to the image by Magento, but I don't understand why it has been resized? Is there anywhere this can be changed?

EDIT

I've now discovered that the image dimensions have been set in vendor/magento/framework/File/Uploader.php

Next is to find the best way to change these values, I found this related post: Magento 2 change max image height and width of image uploader in Admin?

I still don't know why these dimensions have been imposed on users on M2. nor why the file size more than doubles in size!

Answer 1

In the end I created a new theme to override the following two files where the restriction was added:

• vendor/magento/module-cms/view/adminhtml/templates/browser/content/uploader.phtml
• vendor/magento/module-backend/view/adminhtml/templates/media/uploader.phtml

Within those files I hard coded the new max image sizes:

"maxWidth":3000,
"maxHeight":3000

This is the post I followed to achieve the override: https://magento.stackexchange.com/a/153968/191

Regarding the image file size I have not found a definitive answer as to why the size has more than doubled. This post had some insight however: https://stackoverflow.com/questions/14008524/why-smaller-png-image-takes-up-more-space-than-the-original-after-getting-resize

Answer 2

Now the max image size can be set at Stores > Settings > Configuration > Advanced > System > Images Upload Configuration

see https://docs.magento.com/user-guide/catalog/product-image-resizing.html