<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;"><head><meta http-equiv="Content-Type" content="text/html; charset=us-ascii"></head><div class=""></div><div class=""><br class=""></div><div class="">To enhance contrast of your example sketch, to crop it, to erase white space around sketch and export .png file with transparency I used online photo editor Pixlr E. <a href="https://pixlr.com" class="">https://pixlr.com</a></div><div class="">You may erase overall image with 50% eraser to create 50% transparent background image too. The layer with edited image must be unlocked in such case.</div><div class=""><br class=""></div><div class=""></div></body></html>