How to Use the GIMP Filter Pack

Original Photo

Camera filters have long been used by photographers to enhance or correct an image during capture. When shooting film, conversion filters were used to correct for lighting conditions and film types. Special effect filters were also used in analog photography to create diffusion, image repeat and other special effects. Digital photography has made filters all but obsolete, except for use by professional photographers, and many professional photographers also prefer to take care of image problems during post production. Creators of image editing software confuse people about filters because they call their special effect tools "filters." GIMP has a wide selection of special effect filters found under the FILTERS tab. However, GIMP also has a FILTER PACK feature under the COLORS tab that is very useful for making quick image corrections. This article will highlight the use of the FILTER PACK feature of GIMP 2.6.

Things You'll Need

• GIMP 2.6
• A copy of an image for experimentation

Instructions

1. 

   I find this feature especially useful for correcting color casts from scanned images. It is also a useful tool for the novice to make quick corrections to any digital image. For this article, I selected our wedding picture from 37 years ago. The image was scanned a couple of years ago when it was already horribly faded and had a yellow color shift. After you open your image select FILTER PACK from the COLORS menu.

2. 

   The filter pack allows you to make a variety of changes by simply clicking on what you want. Notice that you can apply the filter to a selection or the entire image. To apply it to a selection you need to make your selection prior to opening the filter pack. You can also choose to apply the filter to the midtones, shadows or highlights. Each "window" will open up a series of selectable variations based on the choice.

3. 

   The primary change I want to make to this image is a hue change. After making the hue change, I can then decide if I want to adjust saturation or value. Hue, saturation and value (lightness or grayness) are the three elements of the tri-stimulus color model known as l*a*b or LAB color. In effect, the FILTER PACK allows you to change the working color space or gamut of the photographic image. When I click on HUE, a window of variations opens allowing me to click on one. As soon as I click on the variation it is shown in the "current" image preview.

4. 

   Once I make the hue change and click OK, the image will render in the editing window. If I like it I can save it to a new file name or click on FILTER PACK to make other changes. In this case the image was still too saturated, so I opened the SATURATION window and selected less saturated. Click OK to render the image or click on VALUE to make changes to the value.

5. 

   I didn't want to make any changes to the value for this image, but you can see you are again given three basic variations to choose from. Once you click on any variation in any window, a new variation selection will be presented allowing you to darken or lighten the image again.

6. 

   The ADVANCED menu provides additional fine-tuning allowing you to adjust the actual midtones, shadow and highlight of the image. The changes are seen instantly in the preview window. You can even change the size of the preview image.

7. 

   The final image is a great improvement over the original scan. Resolution lost is never regained and the degradation of the photo due to time, heat and humidity can never be fully recovered. However, images can be greatly and quickly improved using this neat little applet. I don't know why they call it FILTER PACK; it has little to do with camera filters. It is really a LAB or HSV gamut correction tool. In any case, it is another example of an application within a program that can really help anyone make quick image corrections.

Tips & Warnings

• Remember to save corrected files under a new file name.

• Each time you click on a variation it will change the CURRENT view, so don't get carried away.

Resources

• GIMP Software