png images

[#1]

Hi,
I've created some B&W (line) png images for an intranet. On my PC at home they look fine (IE8 as is or in compatability mode).
However on PC at work they look terrible - very poor resolution & lines look perhaps 'jagged' (IE7). What is strange is that this is only at standard zoom setting. If I change zoom level setting (bottom right of IE) to any other level (even 101% or 99%) the images look fine.
Any idea anyone? Thanks.

[#2]

Does it still look bad if you zoom back to 100% after a different zoom?
Sounds like compressed images are being displayed (to reduce bandwidth?) then ooming forces a full loading of the picture.
I used an 'internet accellerator' back ikn the days of dial-up that specifically reduced the resolution of dowmloaded images to make page loading faster, I wonder if this idea is still alive?

[#3]

Quote from: walker

Does it still look bad if you zoom back to 100% after a different zoom? Sounds like compressed images are being displayed (to reduce bandwidth?) then ooming forces a full loading of the picture. I used an 'internet accellerator' back ikn the days of dial-up that specifically reduced the resolution of dowmloaded images to make page loading faster, I wonder if this idea is still alive?

Yes, it still looks bad!

[#4]

Might still be using compressed images and reverting to 'cached' page when the zoom goes back to 100%.
Sorry to say:
1. I'm stumped
2. Best bet is to stop using IE7 (though it's better than IE6)
Seriously though, the so-called compatibility mode' in IE8 definitely does not make it function the same as IE7, our work intranet is set up for IE7 and my Vista laptop uses IE8 which displays many pages far worse than Firefox.  So much for W3C standards.

[#5]

Quote from: walker

Might still be using compressed images and reverting to 'cached' page when the zoom goes back to 100%. Sorry to say: 1. I'm stumped 2. Best bet is to stop using IE7 (though it's better than IE6) Seriously though, the so-called compatibility mode' in IE8 definitely does not make it function the same as IE7, our work intranet is set up for IE7 and my Vista laptop uses IE8 which displays many pages far worse than Firefox.  So much for W3C standards.

Thanks for your interest Grinch but I'm afraid IE7 is the 'standard' at work I've got to live with it for the time being.

[#6]

Just a thought,
have you tried converting any of the images to jpg or simlar, I think IE7 might be more 'friendly' towards these types, this may come across as a moan agains Microsoft but I beleive that png images are an 'open' standard which Microsoft does tend to dislike.

[#7]

For anyone who is interested I've solved the problem which is caused by the way images are scaled (& mine were scaled by php code). An explanation and solution can be found here http://www.zurb.com/article/173/3-ways-to-make-your-site-look-better-in-m. Apparently "the same method of scaling images—something called bicubic resampling—is present in all modern browsers, but it's disabled in IE7."!
This css (from zurb.com) worked for IE7

img { 
-ms-interpolation-mode: bicubic; 
} 

Thanks for looking, regards,
Dast

[#8]

Thanks for sharing.
I suspect that the image resampling issue may be be something that I've come up against in the past.