Zoom Degradation

[nickles]

Hello,

DaveG has made a nice post describing how he sizes his slideshow image files for various zoom percentages in the following thread:

http://www.picturestoexe.com/forums/index.php?showtopic=4481

For the clearest and sharpest picture Dave’s suggestion works great and will result in the clearest zoomed image. Most monitors today are rarely setup to exceed a vertical resolution over 1024 pixels, although it is possible. Most of the newer LCD flat panels, both desktop and Laptop have a native resolution at or below 1024 pixels, although I do have a laptop that has a native resolution of 1680x1050. The vertical resolution is still pretty close to 1024 pixels.

What vary most today are the horizontal resolution and not the vertical. I have played around with Dave’s recommendation with the idea of designing my shows based on a maximum expected vertical resolution of 1024.

Using Dave’s recommendations I decided to design a show for a LCD flatpanel that has a resolution of 1280x1024. For this show I desire a zoom of 200%, which to me is an extreme zoom. According to Dave’s recommendations I multiply the screen resolution by 200% or decimal 2.0. The recommended slide image size would therefore be 2560x2048.

My digital SLR creates a raw image size of 3072x2048. I cropped two images to get a 2560x2048 size and saved the two images(I refer to later as Large). I then resized both images to 1280x1024 and saved these two images(I refer to later as Small). I then used these 4 images to create a PTE 5 slideshow with a 200% zoom into each of the 4 images. I played the slide show and did 4 screen captures of the 200% zoom for each image. I then created a slideshow with PTE 4.48 of these captured images to demonstrate the zoom degradation by not following Dave’s recommendation. I have posted this slideshow as ZoomDegradation and posted here:

http://briefcase.yahoo.com/bc/sknickles@sb...ic+Data&.view=l

You may have to hit your browser refresh button several times to access this file.

I purposely created the slideshow for moving between slides manually with the left and right cursor keys. The zooms labled Large adhere to Dave’s rules and the zooms labled Small are the zooms into the 1280x1024 images. If you bounce back and fourth between the small a large image you can quickly discern the difference in image quality.

My conclusion is that Dave’s technique gives superior image sharpness but….the smaller 1280x1024 results aren’t that “shabby”. There are two advantages to using the smaller image size. The most obvious is that the PTE “.exe” slideshow that is created from the smaller images will be more compact which makes for easier distribution via the internet. The second and maybe more important advantage is that image that must be manipulated by the video card is 4 times smaller. This should be of great benefit for those computers that may have a slower video card with marginal onboard memory…a concern voiced by many about PTE 5. As a general rule of thumb, I would suggest sizing your images for PTE 5 shows to achieve a 1024 pixel vertical size, regardless of the horizonal size or monitor aspect ratio. The show will be as sharp as your original photo for the non-zoomed slides and “not too shabby” for zooms up to 200%. Sharpness will improve the less you zoom. This is the case for general distribution of your slideshows. If you know the show will be viewed only on computers with a high-end video card then Dave’s formula will yield the sharpest results.

This is just my thinking and observations.

Sincerely,

Ken

[davegee]

Thanks Ken,

Did you get my e-mail?

DaveG

[jevans]

Hello,

Using Dave’s recommendations I decided to design a show for a LCD flatpanel that has a resolution of 1280x1024. For this show I desire a zoom of 200%, which to me is an extreme zoom. According to Dave’s recommendations I multiply the screen resolution by 200% or decimal 2.0. The recommended slide image size would therefore be 2560x2048.

My digital SLR creates a raw image size of 3072x2048. I cropped two images to get a 2560x2048 size and saved the two images(I refer to later as Large). I then resized both images to 1280x1024 and saved these two images(I refer to later as Small). I then used these 4 images to create a PTE 5 slideshow with a 200% zoom into each of the 4 images. I played the slide show and did 4 screen captures of the 200% zoom for each image. I then created a slideshow with PTE 4.48 of these captured images to demonstrate the zoom degradation by not following Dave’s recommendation. I have posted this slideshow as ZoomDegradation and posted here:

My conclusion is that Dave’s technique gives superior image sharpness but….the smaller 1280x1024 results aren’t that “shabby”.

Sincerely,

Ken

Hi Ken,

I too have a 1280 x 1024 LCD monitor and I confirm your results. If I had ssen the small zoomed pictures in isolation, I would not have thought them to be too bad. But when you compare them with the large zoomed pictures, there is a noticeable effect. I have been cropping my pictures to 1280 x 960 before putting them into PTE on the basis that this maintains the asepct ratio of my camera, and also, because many of my shows are shown at our local photographic club where the digital projector resizes to 1024 x 768 anyway. But with PTE 5, I think the suggested method is a good idea.

Jeff

[davegee]

Hi Ken,

I have sent you a personal e-mail which hopefully will demonstrate the "white line around shows in PTE5" principle and also how a PTE5 template can be cut down to around 20 Kb so that Forum Members can e-mail very small files between themselves to demonstrate PTE5 Techniques.

DaveG

[LumenLux]

Dave,

It appears you have been doing some useful/helpful work. Any problem in just sharing it all here where everyone has a chance to benefit from it?

[davegee]

Hi Lumenlux,

I have posted a link in "Aspect Ratios" to some demos of Windowed Mode and Skeleton Templates and would appreciate your thoughts?

DaveG