If DefaultSearchProviderEnabled is on, then setting DefaultSearchProviderImageURLPostParams specifies the parameters during image search with POST. It consists of comma-separated, name-value pairs. If a value is a template parameter, such as {imageThumbnail}, real image thumbnail data replaces it.
Leaving DefaultSearchProviderImageURLPostParams unset means image search request is sent using the GET method.
The URL must specify the image parameter using a valid combination of
the following placeholders depending on what the search provider supports:
'{google:imageURL}',
'{google:imageOriginalHeight}',
'{google:imageOriginalWidth}',
'{google:processedImageDimensions}',
'{google:imageSearchSource}',
'{google:imageThumbnail}',
'{google:imageThumbnailBase64}'.