If you really need to shrink an image, and all the easy suggestions don't work, the final answer is to break the image into compressible pieces and recombine them on the client with scripting.
The image from the question looks like a color gradient with vertical lines and some splotches/noise. Break that up into the following layers:
- The color gradient with no lines or noise. This will compress well in PNG and very well in JPEG. Even better, use JavaScript to generate the color gradient on the client. You could probably do it in less than 200 bytes of JS.
- The vertical lines with no color or noise. You could compress this down to a single 4 bit channel (alpha or grey). You only need a 1 pixel tall image, which you can stretch. That would compress very well in PNG.
- The noise. Again, all you need is a single 4 bit channel (alpha or grey). Without color or lines, this should compress very well in PNG or JPEG.
Combine the layers into a single image with JavaScript, and your whole "image" could be 15KB or less.
This sort of work was industry standard in Games for decades, and still is. The great thing is that Photoshop already has all those separate layers, if you created your image like a professional.
Are you using Save For Web...? It should give you options for reducing the size, including color depth. – James P – 2012-07-04T16:02:11.673
You example image is a JPEG file. If you want people to try different tools/methods on it, you should provide one of you PNG file instead...! – Laurent Parenteau – 2012-07-04T23:51:07.667
site uploader converted it to jpg. here is the png file http://s8.postimage.org/z4apal6z9/cw_Copy.png .....please dont use posterize as it wont work with other files I have.....thanks
– Welliam – 2012-07-05T11:59:35.5501That link is also a JPEG. – Dan D. – 2012-07-05T12:03:12.917
this time I am sure it is png http://www19.zippyshare.com/v/69590430/file.html.......thanks for your help
– Welliam – 2012-07-05T14:12:19.373