On the left is the original PNG and on the right are versions reduced to roughly half the orignal size using and
height. See [Link re
I think your answer is in the link from above https://developer.mozilla.org/En/CSS/Image-rendering: 'Currently auto and optimizeQuality are equal by default, both result in bilinear resampling.' 'default value IE8+: bicubic (high quality)'
Next see: http://www.codinghorror.com/blog/2007/07/better-image-resizing.html 'When making an image smaller, use bicubic, which has a natural sharpening effect. You want to emphasize the data that remains in the new, smaller image after discarding all that extra detail from the original image.'
I can think of a couple of possible workarounds, but neither are simple: