original, unedited image
added the initial lightening adjustments
(I mainly duplicated the layer and inverted it, setting it to Soft Light. Then I applied a Levels afterward to get some of the contrast back, by sliding the rightmost and leftmost sliders to where the bump starts and ends.)
The drawing gives off an intense feel, so I chose a random nebula stock I had in my folders and added it on top, layer mode Screen.
To add a more dynamic vibe to everything, I spammed gradients on Soft Light, and messed around with adjustments. The last one was a Brightness/Contrast adjustment, at +150 Brightness. I set it to 70%. This layer is honestly the main contributor in lightening the image, though the steps I took before it were useful as well.