Magento uses the file called view.xml which is maintained at the theme level of the application.

So for example, if you are using the default theme luma you should find the view.xml under vendor/magento/theme-frontend-luma/etc/view.xml

In this file, you would see node inside the node.

The background color of the images is maintained here under the node.

The id attribute value of the node is referenced in the code base.

<image id="product_base_image" type="image">
    <width>700</width>
    <height>560</height>
    <transparency>false</transparency>
    <background>[255, 0, 0]</background>
</image>

Once the values changes have been done, you will have to run

php bin/magento catalog:images:resize

Magento uses the file called view.xml which is maintained at the theme level of the application.

So for example, if you are using the default theme luma you should find the view.xml under vendor/magento/theme-frontend-luma/etc/view.xml

In this file, you would see a node inside the node.

The background color of the images is maintained here under the node.

The id attribute value of the node is referenced in the codebase.

<image id="product_base_image" type="image">
    <width>700</width>
    <height>560</height>
    <transparency>false</transparency>
    <background>[255, 0, 0]</background>
</image>

Once the values changes have been done, you will have to run

php bin/magento catalog:images:resize

Reference: https://devdocs.magento.com/guides/v2.4/frontend-dev-guide/themes/theme-images.html