PNG’s Just Got Smaller.
This post won’t make too much sence unless you’ve read this or this entry where I discuss PNG files, and then amendments to a program resulting from my article.
However, now that is cleared up… moving on.
What’s all this about then?
Since I wrote the article above the software has moved on. PhotoShop has moved onto another version (PhotoShop CS), VIMAS has updated Web Image Guru to v5, and Ken Silverman’s updated PNGOut was released.
So what does this mean for the results I got for their previous versions?
Well a quick bit of testing should solve that question shouldn’t it?
Results
Using the same UnionJack image as last time (which came out as 4.62 kb as a GIF) I loaded up the new software and tested things out, then tried to optimise them with PNGOut. The following is the results:
| PhotoShop | Web Guru | |
| Original | 5.73 KB (5,870) | 3.29 KB (3,373) |
| New Version | 3.29 KB (3,373) | 3.08 KB (3,163) |
| PNGOut | 3.11 KB (3,192) | 2.94 KB (3,011) |
| PNGOut(with new /c3 option) | 3.10 KB (3,180) | 2.90 KB (2,970) |
Notice the new PhotoShop size. They have greatly improved matters here, with their new Save For Web (powered by ImageReady code) performing as well as the old version of WebGuru. Compressing the image with PNGout only serves to reduce the photoshop image down to the smallest obtainable size that was reached with the second PS test in the last article. Not the smallest we could get it, but pretty good, and this does mean that they have solved the awful bugs that PS used to have.
Web Guru 5 performs extremely well, beating the final PNGOut version of the PhotoShop image right from the start. However.. there is an interesting point to make here. Previously WG claimed the image had 99 palette entries, as does PhotoShop currently. However in this new version it only finds 84 entries. Confusingly after comparing the images I could not find any difference in at a per-pixel level.. so this is something of a mystery to me, akin to the original PhotoShop bug of finding 130 entries.
Perhaps VIMAS has managed to optimise their colour analysis, or some other background process that I don’t know about. Whatever they have done certainly these fewer entries will help their final size stay smaller, but seemingly it doesn’t impact upon the actual image. I don’t concider this anomaly to be very important, but I think it was worth mentioning. If anyone can shed any light on this, please tell me.
Compression with PNGOut on both images yeilded significant gains, with the newer /c3 option actually improving matters even more. Finally we can get the image to below 3000 bytes! A challenge I had made previously.
Conclusions
With its Creative Suite (CS) version PhotoShop has closed the gap its previously inept versions had left, and compression with PNGOut on its achieves excellent results, if not quite reaching the optimal. PhotoShop now is a platform that can be realistically concidered for working with PNG web images.
Web Guru however still manages to just stay ahead of PS, but its lead is much less than it was. PNGOut also gets excellent results with the new version, so this would still be my choice of software for now.
However now PhotoShop has caught up with the rest of the world there is absolutely no reason to use GIF for static images. PNG far surpasses it in every respect now, and the industry standard application produces good size files. Just remember that you could be saving over 1.7kb per image in the above example. Thats a lot of saved bandwidth, and a lot of saved money. Plus your pages will load faster, and provide a better user experience.
Its win, win really.
[Update: It has been drawn to my attention that for adaptive images Web Image Guru has some lossy compression going on. Aparently this is a known (if rather sneaky) issue. They say it will be fixed in the next version, for now they recomend using perceptual reduction.]