PapaJohn's Newsletter #40 - Feb 12, 2005

Movie Maker 2 and Photo Story

 

 
 
 Pixels

 
There's an 'Ask PapaJohn' forum at WindowsMovieMakers.net. When Rob Morris started it, I wasn't sure what to expect. What if no-one asks anything? What if too many ask too much? It's worked out pretty well with a healthy balance of questions, and I've been able to answer most.
 
It's a two-way street. The questions often provide inspiration for further learning and newsletter topics. A more experienced forum member asked what seemed like an easy one "If you're heading toward a DVD with your movie, is it better to use still pictures sized at 640x480 pixels or 720x480? Or doesn't it make a difference?"
 
The post was obviously referring to a movie with a standard 4:3 aspect ratio. He had studied the question and found the deeper he looked, the more confusing the answers got.
 
I responded "Yes, it makes a difference and you should use 640x480". Then I went off to re-check it and support what I said...
 
In addition to saying it matters, I wanted to make a visual example. Here's the video snippet I gave him as part of the answer.
 
Pixel Dimensions - Clip
 
It's now a link on the Importing Source Files > Still Pictures page of the website.
 
I'm glad he asked about two specific sizes. The higher question "What are the best pixel dimensions to use for still pictures in stories and movies?" would still be waiting for an answer.
 
Here's a pop quiz: how big is a pixel? is it round or square?1 pixel 
 
You probably know a pixel is small, but how small? The black box at the right is a one pixel JPG image in a 10 pixel wide black border. If I didn't wrap the border around it, I wouldn't know where it is. The pixel is right in the middle. I can see it, but I can't tell if it's square or round. Maybe you can.
 
And here's a red square (on the left) made of 100 pixels - 10 pixels by 10 pixels.
10x10And finally a red image that is one pixel high and 100 pixels wide... the line at the right. If you get into making icons, you'll be working at the pixel level. 
 
 
... before going into it, a couple notes...
 

 
What's Happening? 
 
 My local library (Portage, Michigan) has regular courses, and one of their series is about computer topics. I was browsing through the course list a couple weeks ago, with pretty basic things. There was a class in 'How to Use a Mouse'... I went in and chatted with the director, and offered to conduct something at a higher level - Movie Maker and Photo Story.
 
The director called this week. It seems the library staff discussed it and they are very interested, suggesting an initial session just for them first... so Monday will be the kick-off class for the staff.
 
The PapaJohn gallery at neptune is up and running with a number of videos... and my new website page about how to use the online hosting service is shaping up. 
 

 
Pixels, Dots and Monitor Resolution
 
The Oxford-American College Dictionary defines pixel as: Electronics - a minute area of illumination on a display screen, one of many from which an image is composed (origin - 1960's; acronym from picture element)

Thinking about a tiny or minute area of illumination would seem to imply a point or dot of light... I'd expect a circular disc shaped point of light, not a square. It would be a square only if the single pixel consists of a group of really small dots... and it might be.
 
Paint-OneInchLet's stay in the practical world of making movies, and consider our pixels as small squares on a monitor... the smallest image we can make is one pixel, and the pixel is our unit of measure for sizing our pictures and videos. We don't size things in inches or centimeters; we use pixels... and a pixel doesn't have a specific size... other than being little.
 
As an exercise, open Paint and set the size of the canvas to 1 inch (Image > Attributes > Units of Inches > 1 Wide and High). Then check the size of the canvas in Pixels... it says the 1 inch square canvas on my laptop is 131 pixels wide by 133 high (almost square).
 
It also says my resolution is 131 x 133 dots per inch.
 
The laptop is currently running with a resolution of 1600x1200 pixels. I'll change the monitor resolution to 800x600 and see what Paint says.
 
At the lower resolution, the same 1 inch canvas in Paint is now 66 pixels wide and high... and Paint says the resolution is 66 dots per inch.
 
Paint-800x600
But all those little bitty points of light that make up my computer screen didn't change as I switched screen resolution (the points of light are called pels)... at one resolution there are fewer points of illumination per inch than at the other.
 
The monitor size is fixed. The size of an inch is fixed... but screen resolution and pixel sizes vary from monitor to monitor, and among different monitor settings.
 
Can this be confusing? Yes. Does it really matter for our stories and movies? Maybe.
 
So far I don't think I've made a good presentation about pixels. Let's hope this gets better as we start to use pixels to make images, stories and movies. Let's start with images made with very few pixels.
 

 
Pixel Dimensions, Stories and Movies... Using Small Sized Images
 
Here's a set of 8 square images made from the lowest size of 1 pixel to 100x100 pixels. Paint and IrfanView wouldn't let me make an image smaller than 1 pixel... supporting our basis of a pixel being the measure of a picture or video.
Set of Pix
 
What can we learn from using this set of images to make a story and a movie? Let's see.
 
PhotoStory accepted them all and seemed to be working fine. In addition to putting the images in the story, I added text to each so the story would say what the pixel dimensions of each image was as it played. When I tried to preview the story, I got this error message:
 
PS3 Error
 
This is the kind of error you expect when working with large images or complex projects... this one didn't seem to qualify... but Photo Story 3 obviously didn't like something. It gave a similar message when I tried to render the story.
 
I discarded the first image, the one of one pixel, and the preview and rendering worked fine. But I remembered using a single pixel image in some previous testing. What was different now?
 
What was different was my adding text to the image. I found that, by removing the text label from the one pixel image, the story preview and final rendering worked fine. So it didn't have a problem with the single pixel image, but couldn't handle it if text was included. It had no problem with the text on the other images, 4 pixels and higher.
 
Here's a link to the rendered story.
 
Small Pixel Images - PS3
 
Out of curiosity, I made a 2 pixel image (2 wide by 1 high) and checked it with text... no problems. The single pixel image with text is unique.
 
The light artifacts in the story are from the added text. By the time it gets to the 100x100 pixel image, it's becoming readable. It appears that Photo Story 3 tries to merge the text with the picture at the original pixel size of the picture... if the picture were resampled in PS3 first and the text overlaid on it, the text would be consistently poor or good throughout.
 
Movie Maker handled the full set fine, and I was able to use the normal text overlay feature to label each. Here's the video made from them.
 
Small Pixel Images - MM2
 
Both PS3 and MM2 expanded each image to fill the screen as best they could.
 
Are there any practical lessons from this exercise?
If you want to show a small image at actual size... such as a logo on a black background, put it on a background color in an image that is consistent with the profile dimensions you will be using. Use the image with the logo already in it rather than the logo image itself.
 
A one pixel image can be used in either Photo Story or Movie Maker. If disk space is critical, a one pixel image is lots smaller in file size than something like a plain color picture of 640x480 pixels. But I don't know if the small image would result in a simpler or more complex project file.
 
My one pixel BMP image is 58 bytes in file size... the same one pixel file saved as a JPG is 655 bytes. So the compressed file is more than 10 times the size of the uncompressed one. Compressing tiny things costs you more than you gain by the compression. The crossover point is about 20x20 pixels.

 
Pixel Dimensions - From a Camcorder
 
Video captured via firewire from a digital 8 or mini-DV camcorder comes into your computer as a DV-AVI file... the standard for that format is 720x480 pixels. It doesn't make a difference if you shot the footage at the standard 4:3 aspect ratio or widescreen 16:9... it's 720x480. Of course how you view it varies as the player resizes it...
 
The standard 4:3 aspect ratio view of the captured DV-AVI file will take the 720x480 and show it to you as if it was made of 640x480 square pixels. If it's widescreen then it's shown as if it was made of 856x480 square pixels. This is another source of confusion for many.
 
The world of TV viewing and the discs you make for it (VCDs, SVCDs and DVDs) need MPEG files with rectangular pixels, another point for confusion. As you move back and forth between the two worlds, you're looking at rectangular pixels on TV and square ones on monitors.
 
If you opt to capture your digital tapes to a WMV file, you can choose from all the profiles in the list... but it comes into the computer as a temporary DV-AVI file at 720x480 pixels and then gets transcoded from the temporary file to the WMV.
 
Files captured from analog sources can vary in pixel dimensions with the profile you select. At times I'll capture from my Hi8 analog camcorder using the Dazzle80 and bring it in at 720x480. At other times I'll use 640x480 or 320x240. It depends on what I'm planning to do with the footage... make it part of a DVD project, put it online for computer-based viewing, etc.
 
I usually think through each project from the back end.... how will the viewers be seeing it? Only after determining that will I plan how best to bring video clips and still pictures in. For this newsletter best means the appropriate pixel dimensions.
 

 
Pixel Dimensions - For Discs and TV Viewing
 
TMPGEncTMPGEnc (I'm using version 2.5+) tells you the pixel dimensions it'll be making when converting your story or movie to an MPEG file for a disc. 
 
Select each of the possible choices and read the info about it... a great way to study the options. Here's some of the data - the pixel dimensions:
 
Video-CD - Conventional CD-Video standard - MPEG-1
 
NTSC - 352x240
PAL - 352x288

Super Video-CD - Upper standard of Video CD - MPEG-2 file

NTSC - 480x480
PAL - 480x576

DVD - High Quality Video Standard - MPEG-2 file
 
NTSC -
 - CBR 2000kbps 155min/4.7GB - 352x480
 - CBR 3000kbps 125min/4.7GB - 720x480
 - CBR 4000kbps 100min/4.7GB - 740x480
 - CBR 6000kbps 75min/4.7GB - 720x480
 - CBR 8000kbps 55min/4.7GB - 720x480
 
NTSC (Low resolution) - CBR 1850kbps 165min/4.7GB - 352x240 - quality is relatively sacrificed, but the length of movie can be much longer - with MP2 audio, can be recorded up to 270 min onto standard 4.7G DVD-R - if audio is converted to PCM with authoring software, movie can be recorded up to 165 min onto standard 4.7GB DVD-R
 
PAL - 352x576
 

 
Closing
 
Thinking about and discussing pixels is basic to computer graphics and video work. But pixels can be confusing. Add to that subjects such as dots per inch when scanning, and dots per inch when printing. It's often I hear someone asking what size a picture is in pixels per inch without reference to the number of inches or the total number of pixels.
 
Add the subjects of square pixels of computers versus rectangular ones of TV... and TV unsafe zone that covers some of the pixels.... standard versus widescreen.... different players changing the shape of the object... and on and on. There are many points that one can be confused about, and that's before mixing all the subjects together.
 
We're all learning as we go... I'm currently rethinking the custom PS3 profile I made to save a story when heading toward a SVCD. TMPGEnc says the dimensions are 480x480 and the FAQ at videohelp.com's website says 480x560.... and I can't count the pixels to check.
 

 
Have a great week...
 
PapaJohn