The method could vary depending on your needs. Here are 3 ways to calculate Luminance: Luminance (standard for certain colour spaces): (0.2126*R + 0.7152*G + 0.0722*B) source Luminance (perceived option 1): (0.299*R + 0.587*G + 0.114*B) source Luminance (perceived option 2, slower to calculate): sqrt( 0.241*R^2 + 0.691*G^2 + 0.068*B^2 ) → sqrt( 0.299*R^2 + … Read more
I suspect the path is not correct. As mentioned by user7412219 ubuntu and windows deal with path differently. Try to put the image in the same folder as your Notebook and use:  On windows the desktop should be at: C:\Users\jzhang\Desktop
You should be aware of a few key factors… First, there are two types of compression: Lossless and Lossy. Lossless means that the image is made smaller, but at no detriment to the quality. Lossy means the image is made (even) smaller, but at a detriment to the quality. If you saved an image in … Read more
Support for CSS filters has landed in Webkit. So we now have a cross-browser solution. img { filter: gray; /* IE6-9 */ -webkit-filter: grayscale(1); /* Google Chrome, Safari 6+ & Opera 15+ */ filter: grayscale(1); /* Microsoft Edge and Firefox 35+ */ } /* Disable grayscale on hover */ img:hover { -webkit-filter: grayscale(0); filter: none; … Read more
You could just use some HTML in your Markdown: <img src=”https://stackoverflow.com/questions/14675913/drawing.jpg” alt=”drawing” width=”200″/> Or via style attribute (not supported by GitHub) <img src=”https://stackoverflow.com/questions/14675913/drawing.jpg” alt=”drawing” style=”width:200px;”/> Or you could use a custom CSS file as described in this answer on Markdown and image alignment  CSS in another file: img[alt=drawing] { width: 200px; }