The Online Photography guidelines specify Myer’s Technical, Image and Cropping requirements for each Supplier accreditation level.
Myer Photography Guidelines

GOLD Tier Guidelines
The GOLD Photography Guidelines specify Image requirements for GOLD tiered Suppliers that allow for images with grey backgrounds

How to apply a gradient or vignette to images
Images uploaded in PEP with a grey background require to have a gradient or a vignette applied, to avoid the system from copping into the image. Follow the attached steps to add a vignette in Photoshop.
Grey Background, Scaling and Auto-Cropping