IE11 will not render .png images when Image Effect is applied and nosniff enabled

Summary

When adding .png image and applying image effect on to it, image generated from thumber will incorrectly return with mime type image/jpeg
As a result, when using in combination with X-Content-Type-Options: nosniff set at Apache frontend and IE11 image will not be rendered

Environment

• Microsoft Internet Explorer 11

Steps to Reproduce

1. Inserted an image screenshot.png into a Confluence page and embed it
2. Add an ImageEffect to the picture
3. The generated image is screenshot.jpg
4. Analyze the screenshot.jpg with Apache Tika or HAR file

The following image properties are returned:

Expected Results

The generated image should remain .png and content-type of the image with effects is image/png

Actual Results

The content-type of the image with effects is image/jpeg

As a result, if X-Content-Type-Options: *nosniff *set at Apache frontend, then Image will not be rendered by IE11

Workaround

Issue is not observed by Other Browsers or disable nosniff.