This effect was generated in Filter Forge, a Photoshop plugin that allows you to create your own filters.
Filter does 'light bloom' post-process effect used in video games such as Half-Life 2. Physical concept of light bloom is optical matrix light-striking when scene has too many light. This will result in bright pixels spreading their glow to neighboring pixels. With this filter you can add light blooms to your photos, arts and screenshots.
light bloom post-process glares hdr tonemapping glow luminance