Poor Image resolution

ando775 · Post by **ando775** » Fri Mar 17, 2006 6:29 am

In a slideshow project I'm working on in MSP 8, I applied a moving path, 2D advanced, with a white border to a few pictures, shrunk to about 1/3 of original size and rotated about 28 degrees. (The effect I'm looking for, and achieved other than the poor resolution, was of a "flash" transition, and then the image would appear looking like a snapshot with the white borders.)

As a result, the pictures have jagged edges around the border, but the image itself has very poor resolution. They look pixelated. Now, if I was making them larger than their original size I could understand this, but I don't understand why it's happening when I make them smaller.

Should I be doing this another way? Or is there a way to "smooth" it out? I tried using a blur filter but that didn't help.

Devil · Post by **Devil** » Fri Mar 17, 2006 7:07 am

Just think! Your p-in-p image uses one ninth of the number of pixels that a full size image would take. How do you expect to get the same resolution?

ando775 · Post by **ando775** » Fri Mar 17, 2006 6:49 pm

So, that's just the way it is? There isn't any way around it? What's the point of doing a moving path on an image then if it's going to look crappy?

I don't expect it to be exact perfect resolution, but it's pretty bad looking.

ando775 · Post by **ando775** » Sat Mar 18, 2006 6:03 am

I guess that's a yes then.

heinz-oz · Post by **heinz-oz** » Sat Mar 18, 2006 6:20 am

To the way you are asking, I guess, the answer is a yes.

I have done exactly the thing that you did but did not experience your problems. In order to find out what you should do differently, we need to find out first what you did exactly.

What type of image was it, bmp, jpeg? Since you did resize them, what is the size of them now? What are your project settings? Frame or field based?

Have you tried not to rotate the images? You can rotate the image but you can't rotate the pixels for you video file. This may explain the jagged edges.

ando775 · Post by **ando775** » Sat Mar 18, 2006 6:59 am

Image type is .jpg. The only resizing I did was in/with the Moving Path. It is now W=452, H=267. Lower field first, NTSC (29.97 fps)...

Ok, I think I just solved the problem. I had "perform non-square pixel rendering" selected. On a hunch I just now unchecked it, did a quick preview of the problem areas and it seem to have VASTLY improved the image.

Thanks Heinz! Your prompting was the key. Guess I need to do a better job of checking myself.

Incidently, when should you and when should you not use non-square pixel rendering. I guess in my novice-ness I thought that would be a good thing to use for this project. Obviously that was not the case.

ando775 · Post by **ando775** » Sat Mar 18, 2006 7:33 am

I may have spoken too soon.

After unchecking the non-square pixel rendering box, I previewed the problem images and they looked great...untill I did a "high-quality" preview. When I did that, the images still were very jagged. How can something be supposedly high quality and look worse than the quick and dirty preview?

Anyway, here is the info Heinz asked for...

Image type is .jpg. The only resizing I did was in/with the Moving Path. It is now W=452, H=267. Lower field first, NTSC (29.97 fps). I have tried to not rotate the images, and that lessened the jagging around the white border, but the images themselves were still in bad shape.

Like I said above, how can the instant preveiw look so good, but a high-quality preview and the actual completed video file (MPEG-2 in this case) look so bad? Maybe there is something I'm missing or not getting.

heinz-oz · Post by **heinz-oz** » Sat Mar 18, 2006 9:45 am

What was the original image size? You may be better off reducing the image to near the final size for your project in an image editor like PI or any other out there. The resampling algorithms with image editors are better in reducing or enlarging an image.

In order to make the image smaller, a number of pixels have to be eliminated. The result is depending on the quality of the image editor. In my experience, all resized images need some resharpening. To leave all that to a video editor could be asking for trouble.

I have also found that bmp images give better results when converted to video.

The high quality preview will show you everything exactly as it will be, the quick preview only gives you a quick approximation. That’s why you can see more defects in the high quality preview.

ando775 · Post by **ando775** » Sat Mar 18, 2006 6:08 pm

The original size was W=1536, H=1024. I'll try reducing it in an image editor and saving the file as a BMP and see what that does.

I understand that the high quality preview is supposed to show everything exactly as it will be, it just seem to me that if the program can create an instant preview that looks much smoother it would be able to do the same if it's working harder to create a final video file. I guess I'm having a mental disconnect with this.

Thanks for all your help Heinz.

ando775 · Post by **ando775** » Sat Mar 18, 2006 6:41 pm

Ok...

So, reducing the size of the images in an image editor and converting them to BMP helped a little bit, but I was still getting jagged edges on the white border around the image put in from the moving path dialog box. I went back to project settings again and changed from Lower Field First to Frame-based and this improved things a lot.

So, I've learned a lot from this thread, thanks very much Heinz.

I'm relatively new to this stuff, at least on the technical level, and am still trying to grasp the field vs. frame concept, when to use which one, etc. I'm going to scour the forum and the manual for more info, but if anyone has any rules of thumb you use I would be glad to hear them.