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AstroStudio
06-19-2012, 08:31 PM
1) Script Title: Featured Image Zoomer v1.5

2) Script URL (on DD): http://www.dynamicdrive.com/dynamicindex4/featuredzoomer.htm

3) Describe problem: too much lossy compression applied to "higher resolution image loaded on demand."

Greetings!

When I use a "higher resolution image loaded on demand" with Featured Image Zoomer v1.5, the image is compressed somehow into a low-quality jpeg (even if the source image is a high-quality jpeg or a lossless png file). Is it possible to modify the script or change the quality setting somehow so that the higher resolution image is not so heavily compressed?

Looking forward to your replies,
- Erik Anderson
Ashland Astronomy Studio

ddadmin
06-19-2012, 11:01 PM
The script doesn't apply any "compression" to the enlarged image other than resize it based on the specified magnification relative to the original image. So the only possibility here I can see resulting in a dramatic loss of quality of the hi res image is if the original image and mag level is sufficiently low, and the hi res image sufficiently large, to cause a large amount of resizing down.

If you look at the second "red car" demo on the DD script page (http://www.dynamicdrive.com/dynamicindex4/featuredzoomer.htm), does the enlarged image also look lowly in quality?

AstroStudio
06-20-2012, 07:09 AM
Dear DDAdmin,

Thanks for your helpful reply. I believe now that poor aliasing was the real culprit. I was able to get a noticeable improvement in clarity by scaling the higher resolution image by an exact integer multiplier (4x) more than the preview image.

It may be that the nature of my image is particularly sensitive to this.

Here are my results:

http://www.astrostudio.org/starposter.html

I think it looks great! I'm very happy with this script.

Cheers,
- Erik