quality of still images in vs 11.5 (scanning)

[brucefl]

Got a new Lexmark psc x6570. It scans differnt than my microtek. With the micro. I could set the dpi, and output so I could enlarge a picture with a certain dpi. On this one, I do not seem to have an output size other than the scanned sized. As usual all pictures are different sizes going from 2x2 to 8x10. O know I can take the 8x10 scan 100 dpi, and reduce it.
With smaller ones it can be different, you take a 2x2 and scann 300 dpi, and increase the size (I believe) to make it bigger in vs. I want all of them to look the best they when creating a dvd.
I have no 720x480 setting though I can do that in the program. My concern is with output quality in VS, and size file. I generally do .jpg 600k to 1000k for each picture.
Appreciate thoughts and suggestions on how others do it. Thanks Bruce

[DVDDoug]

So, you can't scan bigger images at 300dpi?

Several factors make still-to-video conversion difficult...

It's best if you start-out with a high-resolution image. I think 300 dpi should be generally be good enough scan resolution, but I haven't used that many still images, and I don't have a good "feel" for that. (A 2"x2" picture probably needs even higher resolution.)

No matter what you start with, the "resolution" has to be converted for video, because images have square pixels and DVDs have non-square pixels. (On a DVD, the pixel ratio is different from the aspect ratio.) Since still images use square pixels, a 720x480 still image has the wrong aspect ratio for video. A 640x480 still image has the correct aspect ratio for a 4x3 video image, but pixels have to be added to get the normal 720x480 pixel array required for an NTSC DVD. (PAL DVD uses a different, higher, pixel ratio, but PAL also uses non-square pixels.)

Colors are also represented differently in video, so there is some color-quality loss with the video conversion.

Of course, when you scan an image there is some quality loss.

And of course, when you blow-up an image from photo-size to TV-size, it's not going to look as sharp... especially a 2"x2" picture!

I'm not 100% sure about this, but I think we are "more critical" of still images than moving images. The quality of still images on a TV seems to be generally worse than regular video, and I think that's because we have time to "study" the image.

[heinz-oz]

There are a few misconceptions at work again. It happens all the time. One of the reasons being that even so called "experts" tend to interchange dpi and ppi resolution freely.

DPI = dot per inch, only applies to an image when printed. Its the number of different colored dots the printer places in a row of 1 inch

PPI = pixel per inch applies to image sizes while these are in electronic form.

If you scan a photo at 300 ppi, the scanner will generate 300 pixels for each inch of your original image.

TV/Video can only display pixel by pixel. It cannot increase clarity by fitting more image pixels into a display pixel. Hence, resolution only refers to the frame size of the TV/Video picture. It doesn't matter what size your TV is 32" or 50", the frame size is the same.

You are best advised to scan to a pixel size of around 20% bigger than what your video resolution is. VS will have sufficient data to convert that to the proper frame size in good quality. High definition uses a different frame size to standard definition but there are a few differing HD ones.

I would also advise to scan to an uncompressed image format like bmp and keep it that way when placing it on the time line. The jpeg compression already discards some image information after scanning in order to reduce the file size. This will be compressed again to mpeg2 for video once you render out your project.

[sjj1805]

You also need to check your scanner software - many have a simple mode and also a professional mode. If you activate the professional mode you should find far more settings available.

[Trevor Andrew]

Hi

If you use an aspect ratio of 4:3 then the image will fill the screen.

The video size for Pal is 720 x 576, unfortunately this is not 4:3, just to confuse the issue, video uses non square pixel rendering,
The same applies for Ntsc.
Square pixels being used for still images.

The minimum size you should use should be 720 x ***
Increasing this size is recommended, especially if you intend to use Pan & Zoom.

As a guide set the scanner to 4 x 3 at 300 this should create an image 1200px -- 900px

[brucefl]

sometimes I am concnered about file size of the pictures, 500kb vs 1mk or 250kb.
You are right about the ppi, I tend to put dpi automatically. It does give me a lot of thought.
May hook up the other scanner.
I can scan higher ppi on this one for smaller pictures with the other scanner I can increase the output size with the scan, scanning a much smaller one with higher ppi, and make it also bigger propotionally right.

Wondering if I scan at a higher ppi, then increase the size afterwards, if I am accomplishing the same thing? as compared to lower ppi, and bigger output size?
thanks

[heinz-oz]

No, it's the higher ppi which will give you a larger image in pixel dimensions. Aim for the right size to start with so you don't need to manipulate it any further except for cleaning it up etc.

Don't forget, use an uncompressed file format to scan to Once you have finalized it and find the file size too big you can still use PI or any other image editor to compress it. However, at a size of around 1200 x 900 px, the file size is going to be small even for a bmp file.

[sj1805]

I have found your user manual:
http://images.lexmark.com/publications/ ... 402_en.pdf


Page 108

[brucefl]

Thanks appreciate, already have the manual, but doesn't give you a lot of advanced choices. It was given to me, nice psc.

Then it actually doesn't matter the dimension size of the pictures, long as the ppi is ample for vs?
I ususally try to make it about 5x7 with a file size roughly 500-1000 kb, so I am looking at the wrong context?

I am always trying to aim for the right size, but seems I need to do a little more studying.

Thanks Bruce

[brucefl]

Let you know what I am doing now.
Scanning ppi, about 150, roughly increase the output size by 120 more or less depending on the picture, gives me a file size about 75-1 meg. , 572 x 568 (more or less) then saving as .bmp. Seems to look alright in the program.
Should I increase size 720 x whatever, but if I do that will also increase the file size possibly to 1.5 meg?
thanks Bruce

[Trevor Andrew]

Hi

The file size in Mb is really irrelevant.

Scan your image to produce an image of 765 x 576px for Pal. This is 4:3 ratio.
It is pointless in scanning at a lower size then using an image editor to resize.
You are best scanning to the correct size in the first place.

This should be the minimum size that you use. 768 x 576
If you are to use ¡¥pan and zoom¡¦ then it may be best to scan to a larger size.

1200 x 900 is roughly twice the size of the video frame, but is using a 4 : 3 aspect ratio.
VS will fit this size to the video frame.
Your quality should be good.

1200 x 900 is a very good option to start with.

If you do not use 4:3 aspect VS will insert a border to fill the gap.

[brucefl]

Right now I am scanning at a resolution of 180 ppi, at 100 % size ratio,
giving me 772 x 661 pixals.
The file size is 1.35 megs bmp.

So, my understanding this should be good, and I have to get into the mindset the 1.35 megs I need to disregard?
Long as I scan a picture at 100%, and increase the resolution to roughly 768 by whatever. It does not matter whether the picture is 2 inches, or 10 inches? Also best to keep it .bmp, though I realize jpg does take a lot of info out.

Appreciate the information, just have to keep it straight in my mind lol
thanks Bruce

[Trevor Andrew]

Hi Bruce

A 772 x 661px should be large enough and not loose quality when using in VS.
If you use Pan & Zoom then you will see a reduction in quality.

The 772 x 661 is not 4:3 ratio.
When you insert to VS one of the edges will have a black border to fill the space.

The measurement you need to concentrate on is the pixel size .

Can you set the scanner to 3inch x 4inch and 300 dip
That will give 900 x 1200.
Its just a matter of mathematics.

Set 6 inch x 8 inch at 150 will give the same size file 900 x 1200

If you want to fill the video frame then you have to use a 4:3 aspect ratio.

[brucefl]

So then if the actually picture size is 3.5 x 3.5
then I should set the ppi roughly 275 ppi?

Problem is I have several pictures that are all differnt sizes,
then a 5 x 7 whould be roughly 175ppi

8x100 would be roughly 120 ppi.

I use the 4:3 ratio. I do understand depending on the size of the picture generally it will have a black border on the right and left size.

I have been looking at the 768 x whatever ratio?
772 x 661 is just what it came to after the scan without being exact.

My older scanner I can set the ppi at any setting I desire too. 110, 150, even and odd number like 107 if I had too.

thanks, Bruce

[sjj1805]

Don't worry about the size in Megabytes of the scanned image.
Once you have the image inserted into your video project and the video has been rendered, the DVD created etc. and you no longer have a need for that large BMP you can delete it from your hard drive and reclaim the hard drive space.

What is more important is to get the picture at a size as near the project settings as possible.
Please view:
What dimensions etc should I use for still images in Videos?