[Android Themes] claimui:
This is a summary of a Galaxy S II thread, but it should be applicable to other Android phones with a pattern lock. Some of this info is elsewhere in bits and pieces, but enough of it is new to warrant a full post. Plus it is helpful to have it all in one place.

Pattern Lock Wallpaper Brightness

Normally the pattern lock wallpaper is not as bright as the original image-- there's a dim or dark filter over it. To change this, decompile framework-res.apk (use apktool or apk_manager), and edit res\layout\keyguard_screen_unlock_portrait.xml.

On line 4, change android:background="#70000000" to android:background="@color/transparent"

Compile framework-res.apk and put it back into system\framework. Reboot and you should see that the pattern lock wallpaper is the same brightness as the original image! You can also try changing the "#70000000" to another hex color code for different effects.

Alternative by LfcFan1977:

Pattern Lock Wallpaper Sizing

Pattern Lock Dots

I found the pattern lock dots to be too large and dark, covering up most of the wallpaper. I wanted to make the dots smaller and more transparent so that I could see the wallpaper but still see where the dot locations are.

The images for the pattern lock dots are in the framework-res.apk, under res\drawable-hdpi. These are png images so if you just want to change the dots, you do not need to use apktool to decompile framework-res.apk. Just open framework-res.apk with 7zip and replace the images directly.

These are the images you need to edit:

btn_code_lock_default.png -- This is the white dot in the middle

indicator_code_lock_point_area_default.png -- This is the dark circular background of the dot

Here are some replacement png's you can try: http://xdaforums.com/showpost.php?p=17806354&postcount=5

For this one, I reduced both the white middle dot and the outer ring by 50%. Then I increased the transparency of both and made the outer ring a lighter gray.

I am not a Photoshop wiz, so I recommend Paint.NET as a free image editor that is relatively simple to use and works well with transparency.

Some other pattern lock dot images you can change (thanks ICWiener_):

Pattern Lock Clock font

The clock font on the pattern lock screen is Clockopia.ttf located in /system/fonts. Replacing this file will replace the font. You can also use the Font Changer app, available on XDA or Market: http://xdaforums.com/showthread.php?t=874658 (You'll find Clockopia in the "Advanced" tab of Font Changer.)

However, simply replacing Clockopia with a normal font results in placement issues. This thread on Rootzwiki gives a good description of the Clockopia alignment problem and how to fix it. Basically, use a font editor to replace the glyphs in the Clockopia.ttf with the glyphs from your favorite font.

As an example, here is a Roboto font replacement for Clockopia, where I replaced each of the Clockopia glyphs with the ones from Roboto. This font now aligns perfectly on the pattern lockscreen.

Pattern Lock Path Color [HELP NEEDED]

Big thanks to pendo for figuring out the pattern lock path color (the white semi-transparent line when you drag a pattern, if you have "Visible Pattern" enabled in Settings.) And also to LfcFan1977 for following up on this.

Sample Pattern Lock Screen

Here is a nice example of a custom pattern lock screen by LfcFan1977.

It would be great to see some wallpapers that incorporate the pattern lock into their design. There could be some pretty cool ideas by mixing a pattern lock wallpaper with custom pattern dots and lines.