CTColorFix
Automatic Full-Spectrum Color-Correction Software

The Only Color-Reference based Full-Color Correction for JPEG Digital Photos

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CTColorFix FAQ



What is Color Correction?
For CTColorFix, Color Correction is the process of adjusting all color values within a digital jpeg photograph to best match how those colors would appear in ideal light. This process includes color hue, saturation and lightness by analyzing the differences between the known color values of your 24ColorCard and the colors captured in your photograph of your card. The process is mathematical and optimized for overall color accuracy.

What is Color Balancing?
For CTColorFix, Color Balancing refers to the part of Color Correction which is primarily involved with color hue and saturation -- and less with lightness (think exposure). The CTColorFix Color Analysis Preservation setting range of [0-to-5] has the ability to selectively reduce the exposure compensation (at the expense of increasing color error) for under-exposed photos. The choice is a subjective tradeoff with color accuracy but sometimes, accurate Color Correction is less asthetically pleasing than simply keeping to good Color Balance.

What is the Full-Spectrum advantage?
For CTColorFix, Full-Spectrum refers to Color-Analysis and Color-Correction which adapts and compensates for a large color Gamut, based on a 24 color reference. Simple White-Point compensation is similar to the default light / color-temperature settings of digital cameras. A single-point RGB shift forces some 'assumed-grey or white' image spot to set R=G=B.

The manual slider and curve adjustments of photo editors provide more individual control over subjectively important colors in a photo to improve Color Balance. However, neither of these approaches can 1) provide compensation for the all too common complex lighting spectra (eg. mixed indoor illumination) or 2) perform accurate color correction which is traced back to a Calibrated Color Reference. CTColorFix Automatically creates lighting-unique, Full-Spectrum Color-Correction profiles and then automatically corrects the related subject photos.

What photo file formats does CTColorFix support?
CTColorFix supports JPEG images which virtually all digital cameras use by default. The filename extension can be either '.jpg' or '.jpeg' variants. At this time, RAW formats, which are non-standard between cameras, are not supported.

What is a Card Photo?
A 'Card Photo' is the photograph you take of your own ColorCard. It is taken at the same time and with the same light as your subject photos. It is a required step of automatic color correction process. If the lighting changes (time of day, different lighting, sun to shade, etc.) then take another Card Photo. Ensure your card is uniformly illuminated with no shadows.

Must I use a CameraTrax color reference?
Obviously, using a CameraTrax color reference card provides the most seamless method to obtaining the best results from CTColorFix. However, CTColorFix will also perform color corrections with Card Photos taken with non-CameraTrax products.

To use an alternate reference:
  • The color reference card must have the exact same 24 color layout as the CameraTrax cards, (which is based on the Gretag-Macbeth default colors set) and...
  • Typically only default color values can be assumed as card-specific patch color values for such cards are generally unknown.
This also implies that the reported color error values can be different from those using a CameraTrax card. Still, for many lighting environments, and additional post-color-correction processing, this may be acceptable. CameraTrax cannot evaluate all possible combinations of other color references and environment lighting.

That said, the LOC-Class license provides the additional Generic Path Color Editor where the default RGB patch values can be adjusted to match a specific Generic card -- IF those values are known.

How important are exact patch color RGB values to the photo's corrected colors?
Very important ... but it also depends on the amount of color correction required and the quality of the environmental lighting. Artificial light, as opposed to natural daylight generally requires more complex correction which relies more heavilly on color card accuracy. Under and over exposure can also push the limits of color accuracy. However, even when color correction differences are subtle, using precise color reference patch color data is so easy, why take the risk of an inaccurate reference?


What are the primary features of CTColorFix?
  • Automatic Color-correction based on your own card's S/N
  • No photo uploading required
  • Local color-correction processing on your own computer
  • Local color-analysis on your own computer option [#]
  • Color Analysis specific to your ColorCard
  • Color Analysis using a generic color reference card (with limitations)
  • Generic reference card patch color editor [#]
  • Post-Correction Color Saturation adjust
  • Post-Correction Exposure adjust
  • Post-Correction detail-preserving Color Annealing option [#]
  • Highlight-Compression compensation Preservation option
  • Zoom-view assist at 1X, 2X and 4X magnification
  • Color-error values and graphics
  • One-Click Image Rotation +/-90, 180 deg
  • One-Click photo skip/add management for duplicates
  • Corrected-image Cropping option [#]
  • Auto-Correction for all photos in current photo group
  • Keep/All filter your best result for all photos in current photo group
  • Rename/Save individual images or copy-all to new folder
  • Quick-clear of all corrected versions after SaveAll copy
[#] Only available with the Advanced License.

How can I try out CTColorFix?
Three fully-working DEMO versions of CTColorFix are available for download direct from the CameraTrax web site. Just select the version to match your computer: Windows 64-bit or Mac OSX 64-bit. Compatability information is listed with the link.

The download software defaults to DEMO mode but is fully functional but only for the sample photos included in the download. However, installing the program is the best way to verify compatibility with your computer and to view how easy it is to automatically color correct digital photos.

Can I install CTColorFix on more than one computer?
You can install the CTColorFIx software on separate computers but a single license cannot be used on more than one computer at a time. For example, if you installed CTColorFix on your desktop and laptop computers, and have only a single license, only one of those computers can perform Color Analysis. However, you can Release a license on your License Registered computer and then Register that license on your other computer. This might be convenient for occasional travel with a laptop while primarily using the program on a desktop for most of your photo processing.

Where can I find the Users Manual?
User's Guides can easily get lost so all the operating information is available in the program's [Help] and [Tour] options when CTColorFix is installed.

What support is available?
CameraTrax is confidant that CTColorFix is very easy to learn and use. Both the [Help] and [Tour} texts, included as an integral part of the program, provide a practical How-To which should answer most questions. If you still need some additional clarity, the CameraTrax web site provides an on-line support request page. Support is available for the first 30 days after license registration and licensed users are given priority. CameraTrax will always try to answer questions in a timely manner.

Will CTColorFix upload my photos?
No. Never. Digital photo data files take too long to transmit and all that data is not necessary for color analysis. Only the colors from your Card Photo are uploaded for analysis and your photos are color corrected locally in your computer.

How long will it take to correct my photos?
It depends. Color Correction time depends on a number of factors. Color analysis, via the CameraTrax Server, is independent of photo image size but dependent on your internet connection, Server activity and your computer speed. Typically Analysis takes only a few seconds. Following color analysis, image color correction can take a little longer and is dependent on photo size and computer speed but is not dependent on the server or the internet. On newer systems, even large photos generally only take a few seconds; the Annealing filter, if selected, will take a little longer.

Will CTColorFix overwrite or modify my original photos?
No. CTColorFix will read your photo image data file to create the color corrected photos but the program will never[#] write to your new photo source folder which holds your original images. Instead, CTColorFix will create a sub-directory below the folder where you saved your original photos. All CTColorFix photo process files are kept there. So, it is best not to save any\ files to that sub-folder as they could be deleted.

Do not save any of your source photo image files to the CTColorFix /Demo folder; create your own folders for your own image files. Any extranious folders or files will be moved to a /CTColorFix/Removed/ folder to keep the /Demo folder clean and organized. The safest choice is to never use the CTColorFix /Demo folder(s) for your own files.
[#] The only exception is when an original photo source filename contains unusual characters which could make automatic image handling difficult for CTColorFix. Those filenames will be slightly edited for compatibility. Normally this should never be necessary.

Do I have to fix every photo; even the duplicates?
No. Using the Film-Strip images, duplicate or unwanted photos can be skipped. After clicking one of the film-strip frames to view the photo, a second click will hide the image and display a vertical RED bar to indicate the skipped photo. There is no change to the original source photos and skipped photos can be added back into the film-strip list by clicking the skip-bar.

Is the CameraTrax 2x3 card too small for taking the Card Photo?
While the 2x3 Card is small, yes, it can be used for taking the Card Photos. Although it is credit-card sized, just use camera zoom or get a little closer. It may take a little more attention to take shadow-free photos, but as long as the patch colors are large enough in the photo to be individually identified, the Card with provide a good reference. Size is not the primary concern; lighting is always more important. The Demo 'Plants' Card Photo is an example.

Must I use both the Grey Balance and Color Cards?
No. With simple color-cast errors of broad-spectrum light, color correction can be accomplished using your camera's auto mode and a clean photo of your card. For more 'difficult' lighting, performing a White Balance [WB] on your camera can help. While some use other types of 'neutral' surfaces for setting the WB, the CameraTrax Grey Balance card is custom designed to provide an optimal neutral reference for setting your camer's internal color temperture setting.

What is color-cast and how do I recognize it?
Color-cast is just the predominance of one band of color over, or in exchange of, another; such as too much blue-green and not enough red. It is easily associated with the difference seen in photos between early morning, mid-day and late-afternoon sunlight. This is the broad-spectrum effect that your camera's 'cloudy', 'indoor', 'snow' settings are designed to offset. However, the combination of simple 'color-cast', various light sources, reflected and artificial light sources, camera-type variances and other factors limit the effectiveness of these simple offsets. That is why CameraTrax color cards and CTColorFix offer a better solution.

What is a "good" source of arificial light?
While there are many sources of arificial light (Incandescent, CFLs, LEDs, Halogen, Fluorescent, HPS, etc., the most desirable qualities are 1) broad spectrum and 2) a smooth spectral output (like mid-day sun). The closest commonly available source appears to be the 4700K Solux Halogen. It appears to have significant use in art exhibits where color is important.

Why is my selection of corner patch colors being rejected?
Be sure to click in the center of each of the four corner color patches in your photo of your ColorCard. However, if the light on the card was not uniform (eg. shadows cast from light filtered through trees) or the lighting was very dark or overly bright, it can be more difficult for CTColorFix to automatically detect the Card and its orientation. This is generally rare and carefully selecting the corner spot locations will usually work. However, if the Card in the photo is really difficult to identify, Color Analysis might also be very difficult with limited performance. Taking good Card Photos is not difficult with a little practice.

Why are some Grey patches in my Card Photo not Grey?
This is a common result of unbalanced light which produces a 'color-cast'. The effect is often more noticeable with the light-grey patch colors simply because of their reflectance.

Why might a color-corrected Card Photo image look less than ideal?
The most common causes are extremely bad lighting and shadows on the Card in the Card Photo. CTColorFix is capable of handling a wide range of poor lighting conditions but there are limits. So if the lighing is not really bad (too dark, narrow-spectrum light, difficult lighting like HPS, etc.) then look carefully at the lighting of your Card in the Card Photo. If the color patches are not uniformly illuminated, that can distort the Color Analysis. When the photos are under exposed, the added color expansion required of the correction process can accentuate the color 'fringing' of the original photo. Try to avoid under and over exposure.

Why could some corrected photos have less detail in the highlights?
The most common example is bright sky in an otherwise underexposed image. Color correction under exposure generally 'pushes' all color lighter and if there is a significant color cast, automatically optimizing color correction will then tend to compress light, or 'washed out' areas. Detail in highlights is thus sacrificed for color. To compensate, the [Preservation] setting of [0-to-5] directs the Analysis process to soften the correction in high exposure regions to keep more detail in exchange for slightly higher color error. The tradeoff is subjective but sometimes visually more pleasing.

Where do I find my Card's S/N?
CameraTrax 24ColorCards are all printed with a S/N. The format is CT24-TT-SSSS where 'TT' is the Card Type ('23'=2x3, '35'=3x5 and '46'=4x6) and 'SSSS' is the 4-digit S/N. When registering, and then using CTColorFix, you will need these two numbers which are used to automatically extract the exact Card's patch color reference data for use during Color Analysis. Note that the patch color data will match that printed on the 3x5 and 4x6 cards but will only be nominal average values for the 2x3 cards (adjusted for S/N).

What if I use the wrong Card Type and/or S/N?
Your color correction results will likely be off but by an unknown amount. Because the card reference data is roughly consistent between Card Types and across all S/Ns, the Analysis process will complete and, in most cases, the results will show better color. However, the most accurate color requires that the correct Card data be used.

Can I use the same Card Photos between different Photo Groups?
No. Well, you could, but unless the light were exactly the same, the Color Analysis would likely produce incorrect results. Since taking a Card Photo is so easy, why short-cut your color by 'faking it'?

What is a Photo Group?
Relative to color correction using CTColorFix, a Photo Group is a collection of photos that 1) contain at least one Card Photo and 2) your subject photos where ALL photos were taken in the same light.

Where do I find my color-corrected image files?
All color corrected photos are saved to a directory/folder called '/ct24' which CTColorFix automatically adds to the folder where you saved your photo group. You can, however, specifically save the corrected image being displayed to another location using the [SaveAs] feature. The SaveAs[ALL] provides a simple way to copy ALL color corrected versions of ALL subject files within the Photo Group to another user-selected folder.