Making Picasa Sliders Reduce Values

Picasa is a very neat, very quick, photo-processing tool, providing the tools to make most basic adjustments to photographs. For reasons known only at Google, many of the controls allow only increases in adjustment -- you can't make a decrease in the value. You can see this below, where the Fill Light, Highlighs, and Shadows sliders are all the way to the left.

Look at the Color Temperature slider though. It allows both increases and decreases in values. We'll change the Picasa configuration file to make the other sliders mimick this behavior allowing both increases and decreases on the sliders. So now instead of just being able to darken shadows, we can now lighten them too, as well as being able to both intensify highlights and dull them, etc.

Step-by-Step

Here's what you need to do:

  1. Close Picasa. Don't have Picasa running when you make these changes.
  2. Make a copy of filterdesc.xml. This will be your backup if things go wrong, or you want to undo your changes. This is located in different directories for different operating systems:
    • Windows: C:\Program Files\Google\Picasa3\runtime
    • Ubuntu (running Wine): /opt/google/picasa/3.0/wine/drive_c/Program Files/Google/Picasa3/runtime
  3. Edit filterdesc.xml using Notepad, or whatever non-Word editor you have. (In Windows you could right click on filterdesc.xml, select "Open with Notepad".)
  4. There are 3 sliders we're going to change; we'll add an <offset> value to the Fill Light, Highlights, Shadows sliders. (The Color Temperature already has a centered slider.) Look for the section labeled <!-- TUNING2 new version with Kelvin color temp --> -- about 1/3 of the way down the file. This is where the sliders are defined. Replace the existing section with this, which simply adds an offset value for the three sliders, giving us a basic centered slider:
    	<!-- TUNING2 new version with Kelvin color temp -->
    	<filter id="finetune2" mode="soft" zerostate="zero">
    		<label>Tuning</label>
    		<cursor type="dropper" persist="0"/>
    		<colorcircle id="0"/>
    		<sliders>
    			<slider id="0">
    				<label>Fill Light</label>
    				<range>1.0</range>
    				<offset>0.5</offset>
    			</slider>
    			<slider id="1">
    				<label>Highlights</label>
    				<range>0.48</range>
    				<offset>0.24</offset>
    			</slider>
    			<slider id="2">
    				<label>Shadows</label>
    				<range>0.48</range>
    				<offset>0.24</offset>
    			</slider>
    			<slider id="3">
    				<label>Color Temperature</label>
    				<range>2.0</range>
    				<offset>1.0</offset>
    			</slider>
    		</sliders>
    	</filter>
    
  5. Save the file.
  6. Restart Picasa.

Here's what you should now see:

The Details

Each slider is defined with a number of settings. You'll notice that in the original the sliders for Fill Light, Highlights, Shadows don't have an <offset> value, whilst the Color Temperature does.

  • <label> defines the text label for the slider. No need to change this.
  • <range> defines the total amount of effect -- the range between the upper and lower bounds. Changing from 1.0 to 2.0 will produce a much larger effect with the same movement of the slider.
  • <offset> defines the slider starting position. Typically you'd want the slider to start in the middle so set the value to 1/2 the value of <range>. You might also want to provide a little more room for increasing values, so set the slider to 1/4 of the value of <range>.

If you don't set an <offset> the slider will start all the way to the left, basically the default behavior.

Alternate Settings

If you find the that moving the slider a little applies large changes and would like to make more use of the whole range of the slider, try these values (first number is range, second number is offset):

  • Fill Light:
    <range>1.5</range>
    <offset>0.375</offset>
Alternately:
  • Highlights:
    <range>3.0</range>
    <offset>1.5</offset>
I like to add some shadow to my images, so here's what I prefer to use:
	<!-- TUNING2 new version with Kelvin color temp -->
	<filter id="finetune2" mode="soft" zerostate="zero">
		<label>Tuning</label>
		<cursor type="dropper" persist="0"/>
		<colorcircle id="0"/>
		<sliders>
			<slider id="0">
				<label>Fill Light</label>
				<range>2.0</range>
				<offset>0.5</offset>
			</slider>
			<slider id="1">
				<label>Highlights</label>
				<range>0.48</range>
				<offset>0.24</offset>
			</slider>
			<slider id="2">
				<label>Shadows</label>
				<range>1.0</range>
				<offset>0.5</offset>
			</slider>
			<slider id="3">
				<label>Color Temperature</label>
				<range>2.0</range>
				<offset>1.0</offset>
			</slider>
		</sliders>
	</filter>

FAQ

Error: Cannot create filterdesc.xml

In Windows Vista you might get an error "Cannot create the C:\Program Files\Google\Picassa3\runtime\filterdesc.xml file", "make sure path & file name are correct".

In Vista you must run with administrators rights in order to make changes to filterdesc.xml.

I don't like the new settings

Simply delete the changed filterdesc.xml, and rename you backup copy back to filterdesc.xml.

Things went horribly wrong...

In the worst case you can reinstall Picasa. That should overwrite everything to new as it should be. Your previous settings will not be deleted -- this is the same as what happens when you install a new version of Picasa.

References

This information was primarily based on prior posts from dpreview and Picasa Groups.

Comments

  1. By misha, on December 02, 2009, at 12:10 AM
    Amazing post! Also works in Mac, go to Open Package Contents on Picasa.app
    The file is in ContentóResourcesóruntime folder
  2. By vegh319, on September 10, 2011, at 05:56 AM
    Thats what i've been lookin for! Thanks for this!
    By the way i don't get why developers set those values as default...
  3. By daveg, on September 13, 2011, at 08:37 AM
    @vegh319: Guess the focus is on simplicity, although in this case I suspect more people are confused as to why they cannot reduce value.
  4. By osman, on March 01, 2012, at 01:36 AM
    thanks a million...
  5. By Paulo Barretto, on April 19, 2012, at 01:27 PM
    Please read this!
    As many others, I have made in filterdesc.xml the modifications you suggest, and couldn't use Picasa without them.
    Now Picasa has a new version 3.9, and Google introduced a new class of filters, which appear in filterdesc.xml under the name "GLIMMER FILTERS". For these the xml specifications are far more complex, so that you can take one the filters (without changing its id string) and completely modify its controls and actions. Take a look at it and you will understand better than with any explanation i try to make. I've got some amazing results just playing around!
    But there's another fact which is also amazing. I could not find a word in internet about that subject. Absolutely nothing! So I am sharing this absurd "open secret" with you, and asking if you have any information about it. If you do, please let me know.
  6. By ln, on August 28, 2012, at 09:04 PM
    Outstanding holmes. Really appreciate this. I'd hosed up some important picts setting the iso too high and no longer have ps, so this is MONEY!
  7. By Wayne, on May 29, 2013, at 08:59 PM
    Excellent fix for this problem. Works now exactly as the program should, had it been designed more friendly in this control. Thanks !!!!
  8. By peter v, on August 03, 2013, at 09:51 AM
    very good! thanks for this, you're a genius!