[UserStory] fix code style errors in DisplayImage.java

[robo-jones]

User Story

Essential components

• Title describes the story
• Stakeholder type is identified
• Outcome is described
• Rationale is explicit
• Acceptance criteria are verifiable and from the perspective of the stakeholder

Story

As a maintainer
I want the code in DisplayImage.java to adhere to the syntactic style conventions of the project
so that the project code has a consistent style that facilitates maintainability.

Supporting Information

Comments matching 'TODO' are reported by Checkstyle but are not coding convention violations.

Dependencies

Issues #32 and #33 depend on this user story

Acceptance Criteria

Checkstyle reports no errors in DisplayImage.java.