Color Correction


Sample Area

The sample area is a semi-automatic feature of ColorWasher. You can perform the most accurate color corrections with it if you use it correctly. The displayed sample area marquee looks similar to what you know as selections in various image editing applications, but it is used for a totally different purpose. The area that is enclosed with the marquee is only evaluated by ColorWasher for measuring the color cast.


Creating a Sample Area

If the sample area tool above the preview is not active, please click on it to activate it. To draw the sample area click on the preview, keep the left mouse button pressed and move the mouse to draw the marquee. The enclosed area is the sample area which will automatically be evaluated by ColorWasher. ColorWasher will then fill the source target box with the measured color of the color cast and set the Target color box to neutral gray. Additionally the color correction will be applied to the preview image.

If the Instant Preview check box is activated, the calculated color correction will be applied to the preview while you are drawing the sample area marquee. This gives you an immediate feedback of the effect of the sample area and helps you to create a suitable one. If you have a slow computer you should deactivate Instant Preview or make the preview image smaller with the zoom buttons.

Where to Create a Sample Area

Creating a sample area above a sufficient image area can be a tricky business. Here are some rules of the thumb concerning sample areas:

1. Create a sample area above an area of the photo that was white or neutral in the original scene.

2. Use the Neutral check box on the Info tab sheet to get an idea about which part of the photo is suitable for a sample area.

3. Make the sample area as large as possible. If you have several choices in the photos, better create it above a larger object than above a very small one.

4. If the white or gray object in the photo is round don't let the sample area marquee exceed its borders. Better to leave a part of the object uncovered than to make the sample too large.

5. Creating a sample area above an area that is too dark or too bright usually produces unsatisfactory results.

6. If you have some objects in the image with different gray variations, try all of them and keep the sample area that produces the best results.

7. Activate the Neutral check box on the Info tab sheet to make ColorWasher blend out image areas that are not suitable for a sample area. The remaining areas are usually good candidates. But don't trust this feature too much as it can fail for some images.

8. If there is no pure white or gray area in the image, try an almost neutral area, e.g. a washed out sky, grayish water or color-poor clothes.

9. If you have more photos with the same color cast, try to find one with a previously gray or white area. Use the sample are on it and correct the other photos with the same settings.

10. If nothing helps, better try the Auto buttons or manual controls.

Places of creating a sample area could be gray clothes, a white T-shirt, white cloth, a white or gray paper, the white area in an eye, teeth, gray asphalt, clouds, white furniture, white walls or snow. But please try to comply to the rules above. A part of the image that looks good for placing an sample area may not work well if it is too bright or dark.

Please remember: You will get better at creating the correct sample areas with every new image you try. It might take a bit of time to become an expert, but it is worth practicing this technique. It allows and sometimes even demands some creativity from you and can help you produce the best color correction results. Everyone can press an Auto button, but creating a sample area needs a bit more skill.


Sample Area Hints

The text box at the right bottom displays hints that refer to the sample area that you created. This can be quite helpful if you don't have much experience with drawing the sample marquee.

If the area which is enclosed by the sample marquee is too dark or too bright, the text box will let you know. You will also get a warning if the sample area is too small or encloses an area that is too colored. If you get such a warning and are certain that you have done right or can't find a better area to sample, please ignore the warning. If the Instant Preview check box is activated, the text box will already display recommendations while you are still creating a sample area.


Moving the Sample Area

Sometimes you create a sample area that doesn't fit that good. In this case you have two choices: You can try to create the sample area again or you can try to move the current sample area marquee. To move the marquee hold down the CTRL key and drag the sample area above the preview.

This technique can also be used to search the image for a right place for the sample area, especially when you have the Instant Preview check box activated for receiving immediate feedback.


Creating a Second Sample Area

For very difficult photos it can help greatly to draw a second sample area in a different part of the image to produce a more balanced color correction. To create a second sample area hold down the shift key, click on the preview, keep the left mouse button pressed and move the mouse to draw the marquee. If you want to redraw the second sample area, perform the same action again. If you redraw the first sample area, the second sample area will be preserved. To get rid of the second sample area while preserving the first one, please right click on the Reset button and select "Remove 2. Sample Area".


Visual Examples

Here are some example that demonstrate where to create a sample area:

The snow in this photo looks very blue. The Neutral check box on the Info tab sheet shows very clearly were we can place our sample area.
We placed the sample area in the largest white area and get a very good result. That was easy!

This image has a strong yellow cast as it was taken indoors. The Neutral check box shows that we could select the drawing at the top or some parts of the table cloth. The pullover of the old woman wouldn't be a good choice as I remember that it originally was not pure white or gray.
All four sample areas that you can see in the image would work nice. We decided to use the one at the bottom middle as it is the largest. Wow! No yellow cast isn't visible anymore and the colors became real vivid.

This is an old photo from the 70ies. It became quite faded and yellowed in the meantime. The Neutral check box shows that it is best to select the ground. Asphalt is often a good choice for a sample area.
The Linear Cast Type produces the best result with this photo. The color are reconstructed quite nicely. The photo also gets that nostalgic old look again.


Advanced Sample Area Techniques

In some cases it might prove profitable to use the sample area marquee in an unusual way. For artistic effects you could select an area that is not really gray or white. Moving the sample marquee to do that can be fun.

You could use the sample marquee (similar to the eyedropper) to load a certain color into the Source box and then manually adjust a Target color of your own. This method can be used to color-correct a photo and to colorize it at the same time, but you can also do that if you want to convert a certain color in the image to another color.

Selecting neighboring image areas with different gray or white variation can produce better results sometimes. This makes sure that more or less the average of these gray variations is sampled. This technique can sometimes improve the color correction quality and helps you cope with tricky photos that contain more than one color cast.

If a part of a image has a different color cast than the rest of the photo, please create an image selection in your image application for it and use ColorWasher only on that selection. Such a case is demonstrated in the following example.


Advanced Visual Example


A friend of mine purposely set up a very difficult-to-color-balance shot to test our color correction skills. It consists of a few objects, a live monitor display, and lit with halogen spots and one weak tungsten overhead lamp. Our friend was so kind to white balance to the halogen lamps only. Grrr.... This really looks like a color-correction nightmare...

 OK, lets do this step by step. First of all we want to get rid of that red cast at the bottom. We place our sample area at left bottom and try each of the Cast Types. Luckily the Linear cast type manages to remove the red casts completely. Hurray! But the screen still looks very unnatural.

OK, we need to color correct the screen only, so we create a feathered selection of the screen in our image application and run Color Washer on it. We create a sample area at the top right of the screen and switch back the Cast Type combo to Auto detect. Good, there's no color cast on the monitor anymore. As a final step, lets try to give this shot more depth. In ColorWasher we use the Reset button and decrease the Highlight slider to makes the monitor a bit dimmer and increase the Shadow slider slightly. Looks like the photo has more depth of field now. My friend is going to get real envious about our skills :-))).