| All About Themes |
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Themes for Pocket PC's are just archive files containing at least one image and
a configuration file with the color setting in it.
The .tsk file is actually a Windows CAB file which is an archive file something
like a ZIP file. It contains other files. The .tsk extension tells
the Pocket PC Operating system that it contains files and settings for the
Today screen.
The image files in the .tsk file have special names that tell the Pocket PC
which ones they are. There are usually two images in a theme file.
The main image that is displayed in the background of the Today screen and an
image for the drop down menu.
A Microsoft SmartPhone theme file is slightly different. It is still a CAB
file but it has a .hme extension. It only has one image since a
SmartPhone does not have a drop down menu. And the file that has the
color information is an XML file that has settings for numerous screens in a
SmartPhone. Also with SmartPhones there is the option of using another
XML configuration file to control the theme and the placement of plugins on the
Home screen. Themes made with ThemeMaker SP do not use that format.
The images have different size requirements depending on which platform they are
designed for. Here is a diagram that trys to explain the size
requirements for the main images of three of the Pocket PC Platforms.
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| The vertical dimensions are from the bottom of the Navigation bar (Title Bar)
to the bottom of the screen. Here is another diagram displaying the
components of a QVGA screen showing the realationship of the command bar.
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| Here is an overlay of the portrait and landscape views of a QVGA theme showing
the areas of the main image used in the display. |
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| On themes with drop down menus there is an image for the menu and it can be the
same image as the Today screen image. When the image in the
menu is the same as the Today image it creates a transparent effect like
this example. |
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You will notice that the menu can overlap the command bar and that is why the
image for the menu should be long enough to extend to the bottom of the
screen. The width of the menu is dependent on the longest entry on the
menu. It does have a maximum width though and varies depending on the
device. To be safe all our ThemeMaker programs create the same size main
and menu images and exted from the bottom of the Navigation bar (Title Bar) to
the bottom of the screen as we do not have control of what Microsoft may do
with the screens.
The early Pocket PC's before Pocket PC 2003 came out did not allow you to change
the color of the text on the drop down menu. It is always
black which causes problems if you have a dark image for the menu. Many
Theme creation programs gave you an option usually called "Transparency" that
allowed you to blend a white image on top of the image in the menu to create
more contrast to see the dark text. This also would degrade the
image by giving it a milky look. Our ThemeMaker programs have this option
for both the Today screen and the Menu but it allows you to change the color of
the overlay so you can keep the intregity of the Theme.
Themes for devices from Pocket PC 2003 on have a setting for the menu text color
as in the above example where we have set the text to white.
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The Pocket PC OD treats the images for the Today Screen and the Menu
like a browser does for background images. It will tile them if they are
smaller than the screen size. If you installed a theme Made for a
Standard Pocket PC into a VGA Pocket PC it would tile the image in the
background.
This is one way that Microsoft reduced the file sizes of their themes they
provided on the devices by using a strip of an image for the menu, that had a
small files size, and the os would repeat it filling the menu.'
For the new SE QVGA and SE VGA devices they made another change to the
configuration file allowing the use of one image in both the Today screen and
the Menu. Thus saving in files size as these new larger screens require
larger files.
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To load a theme into a Pocket PC you have to copy the theme into the
device. The default location for the themes is in the My Documents
folder. Then tap on Settings from the drop down menu and tap on the Today
icon. A list of avilable themes will appear. Tap on the one you
want then tap on the OK.
There are other programs available that manage the themes on your Pocket PC and
allow you to view the image before selecting it. Or they can randomly
display a new theme every day or when you turn it on.
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BANDING
As of this writing, there is no Pocket PC or SmartPhone that displays color
images in any greater color depth than 16 bits or 64K colors.
If your device has a screen that is 240 x 320 pixels in size that means in could
display 76,800 different colors at one time. But the electronics that
display the colors limit to a maximum of 65,536 (64K = 65,536 / 1024). On
a standard Pocket PC 240 x 320 screen the area that displays the main image is
240 x 268 pixels in size which equals 64,320 pixels in area. Which means
that a display that has a maximum capability to display 64K colors is just
right for that screen. Up until the SE devices came out that was fine but
now that much higher resolution screens are out like 480 x 640 we have a
problem. There are physically more pixels being displayed than the
electronics are capable of filling with different colors.
KAMware ThemeMaker programs create images that are either 8 bit or 24 bit color
images. A 24 bit image can display up to 16 million different colors at
one time. A 480 x 640 display 307,2000 pixels. But the electronics
can still only create 64K different colors at one time. If a theme has a
24 bit image in it and it is displayed in a device that is capable of only
displaying 64K colors then something is lost in the translation.
Some images will not noticeably be effected and some will be grossly effected.
Here is an example:
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The above image was captured from ThemeMaker X on a PC that is capable of
displaying 24 bit images. As you can see the image is crystal clear and
detailed.
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This is the same image captured off a 480 x 640 HP 4705 Pocket PC. Notice
the banding in the blue sky! This image has more than 64K different
colors in it so the OS in the Pocket PC does it's best to interpert the colors
and adjust them to the lower color count. Usually complex images with
gradient areas will produce the banding effect you see here. Even if you
converted the image to 16bit in an image editing program you will get banding
in the gradients. Notice that the complex areas of the image, such as the
smoke, do not seem to be effected. They do have their color count reduced
but the human eye cannot see the changes as easily since they are usually
too small and that part of the image is very complex. The smoke in the
64K image does look sharper as many of the pixels in the smoke that give it the
"smokey" look are averaged out and made the same thus sharpening it some.
Notice the gradient in the Navigation Bar (Title Bar) is also changed.
Althought the Navigation and Command bars of a Pocket PC are not part of
the image of a theme they share the screen with it and the amount of colors
used in them effect the way the image is displayed. So if you do have an
image with some gradient in it you may want to make the Navigation Bar a solid
color so the image has more to work with and thus have less banding.
Keep this in mind when preparing images to be used on these devices. In
this example one way to fix this would be to select the sky, delete it, then
fill in the area with a single blue color.
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Click here for some tutorials on
creating Themes. |
