Adjust Saturation (a filter plug-in for Adobe Photoshop™ 3.0)
Free 68k version 1.0.1. Copyright 1996 Hugh Kawahara. All rights reserved.
§ 0. Quick Start (This section should be enough for most people.)
0.1 Distribution Policy (Yes, it's free!)
This 68k version is a freeware. Please read § 1 for the detail.
0.2 System Requirement
Any Macintosh computer running Adobe Photoshop™ 3.0.0 or later.
0.3 Installation
Move the entire "Adjust_Saturation" folder into the "Plug-ins" folder in your "Adobe Photoshop™" folder. (Re)Start Photoshop. It will appear under the menu "Filter->colleen".
0.4 What It Does
It works on RGB images only. You can increase or decrease the overall saturation of the image.
You can also set the "contrast" of the saturation. By increasing this contrast, you can saturate
the already saturated part even more and de-saturate the un-saturated part. This plug-in
preserves either the luminance Y = 0.30R + 0.59.G + 0.11B or the intensity I = (R + G + B)/3.
Preserving the luminance would make the image look more natural in most cases.
0.5 Usage
Use the "Gain" and "Contrast" sliders to adjust the saturation.
Use the radio buttons to select whether it preserves the luminance or intensity.
The plug-in creates a small thumb nail in the dialog box for quick preview and a full size
preview window over the original image window. Both previews are zoomable and scrollable
and the full size preview is resizable. The original image window still exists behind the full
size window. Use the "Glass" and "Hand" tools in the dialog box to zoom in/out or scroll the
previews. Double click to the toolbox fits/zoom-in the thumb nail preview. Double click while
holding down the option key fits/zoom-in the full size preview. Hold down the option key and
click on the "Cancel" button to reset all parameters.
0.6 How to Reach the Author
Please send comments, bug reports, etc. to <kawahara@leland.stanford.edu>.
Visit <http://www-leland.stanford.edu/~kawahara> for updates.
0.7 Examples
The following pictures are to show how this "Adjust Saturation" filter works. The picture
below is the original photo ("Shuttered windows" by Don Cochran) taken from a photo CD.
It's already adjusted well, so it may not be a terribly good example.
The saturation was increased on the left photograph using Photoshop's "Hue/Saturation"
adjustment with Saturation = +50 . You'd notice two problems. One is that the wall is too
yellowish and the other is the leaves are too bright. On the right one, "Adjust Saturation"
filter was used with Gain = +60%. The leaves are not too bright anymore because
"Adjust Saturation" maintains the luminance, but still the wall is yellow.
To solve the problem of the wall, the "Contrast" of the saturation was increased to +100%
with Gain = +60%. This should de-saturate and remove the yellow cast on the wall, because
the wall is much less saturated than the flowers and the leaves. The result is on the left.
To explore the effect of the "Contrast" more, the "Gain" was decreased to +40% with
Contrast = +100%. Also, the "Linearity" (hit the "More" button) was set to 100%. The result is
on the above right. The wall and window is almost in B/W, while the flowers and leaves are
still in well saturated color.
User's Guide
Contents
1. Distribution Policy and Legal Stuff
2. System Requirement
3. Installation
4. What It Does
5. Usage
6. Misc. Notes
7. Version History
8. How to Reach the Author
9. Acknowledgment
§ 1. Distribution Policy and Legal Stuff
This particular version (the version is specified at the top of this document) is a freeware.
Other versions may not be. You may distribute this software freely as far as no parts of the
contents of the folder "Adjust_Saturation", which includes this memo "Adjust_Saturation.doc"
and the plug-in "Adjust_Saturation.68k", are deleted or modified.
The author retains the copyright. This software is provided "as is".
The author shall not be liable for any damages or losses caused by this software in any way.
§ 2. System Requirement
Hardware:
Macintosh computer with MC68020 processor or greater, including Power PC.
Math co-processor (FPU) is NOT required.
Software:
System 7.0 or greater.
Adobe Photoshop™ 3.0.0 or greater.
Since Photoshop 3.0 requires MC68020 and System 7.0, any Macintosh computers running Photoshop 3.0.0 or greater should be sufficient to run this plug-in.
It will not work with prior versions of Photoshop.
§ 3. Installation
Simply move, copy, or drag the entire "Adjust_Saturation" folder containing the plug-in and
this memo into the "Plug-ins" folder in your "Adobe Photoshop™" folder.
Quit Photoshop if it is running. Then (re)start Photoshop.
It will appear under the menu "Filter->colleen".
§ 4. What It Does
4.1 Image Mode
RGB images only.
4.2 What It Really Does
It adjusts the saturation in a different way from the "Hue/Saturation" adjustment in
Photoshop. The differences are:
1) Can adjust the "contrast" of the saturation. With higher contrast settings, it saturates
saturated colors more and de-saturated un-saturated colors. With lower contrast
settings, it sets the saturation evenly. This feature is useful when you try to saturate
images that have gray or white parts. Usually these gray or white parts get a "color cast"
when saturated, unless they are perfectly colorless. By increasing the saturation
contrast, you can ease this problem. You can also create a "partially" B/W image by
decreasing the saturation with a high contrast setting.
2) Use a "milder" mapping curve between the initial saturation and the final saturation.
It works more naturally (hopefully). This can be overridden by the "Linearity" slider.
See the section "About More Button" below.
3) Preserves the luminance Y = 0.30R + 0.59G + 0.11B or intensity I = (R + G + B)/3.
The luminance Y approximately corresponds to the "panchromatic brightness".
Preserving the luminance usually makes the image look more natural.
§ 5. Usage
5.1 Invocation
Simply choose "Adjust Saturation…" from the menu "Filter->colleen".
5.2 Adjusting the Gain and the Contrast of the Effect
Use the "Gain" and "Contrast" sliders
5.3 Choosing the Preserving Variable
Select the "Luminance" or "Intensity" radio button.
5.4 Resetting the Settings
Clicking the "Cancel" button while pressing the option key resets all parameters to the
default values except for the radio buttons.
5.5 Previews
The plug-in creates two previews. One is a small thumb nail in the dialog box
and other one is a full size preview over the original image window.
The full size preview window is a separate window from the original image window.
To view the original image, just drag the preview window.
Both previews are zoomable and scrollable. The full size preview is resizable too.
Use the "Glass" tool to zoom-in/out the preview. Use the "Hand" tool or the scroll bars
to scroll the preview. Press the option key to zoom out. Press the command key to zoom in.
The maximum zoom-in ration is 1:1 at this moment.
To choose a tool, click the toolbox in the dialog window.
Double click the "Hand" tool to fit the thumb nail preview to the preview area.
Press the option key while double clicking to fit the full size preview to the window.
Double click the "Glass" tool to zoom in the thumb nail preview to 1:1 ratio.
Press the option key while double clicking to zoom in the full size preview.
The double clicks do not resize the window .
(Note: The thumb nail preview is "buffered" for quick refresh.
Any zooming or scrolling may take some time to re-buffer the data from Photoshop, if the image is large.)
5.6 About "More" Button
Push the "More" button to get more options. These are for more precise adjustment.
The "Linearity" slider lets you adjust the mapping curve. With Linearity = 0% (default),
the filter uses a quadratic mapping curve between the initial and final saturation.
With Linearity = 100%, it uses a linear curve which results more radical effect.
The "Luminance" part has three sliders named "R", "G", and "B". Those sliders let you re-define
the luminance. The "B" slider is always disabled and dimmed.
§ 6. Misc. Notes
Black and White is beautiful.
§ 7. Version History
1.0.0 Initial release.
1.0.1 Bug on masking the effect fixed.
§ 8. How to Reach the Author
Please send comments, bug reports, etc. to <kawahara@leland.stanford.edu>.
Visit <http://www-leland.stanford.edu/~kawahara> for updates.
§ 9. Acknowledgment
This software was developed using
Metrowerks CodeWarrior Academic 7 and
Adobe Photoshop 3.0.4 SDK.
Adobe Photoshop is a trademark of Adobe Systems, Inc..
Macintosh is a trademark of Apple Computer, Inc..
Metrowerks CodeWarrior is a trademark of Metrowerks, Inc..
