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Using the BestMatch Function

Question:  How do I use the BestMatch option in my X-Rite eXact?

Answer:  X-Rite provides a unique function in their X-Rite eXact spectrophotometer that can help the press operator achieve color match on press by just changing the density of the ink.

Many times a press operator is faced with a dilemma. Can they achieve the color the client wants on press with the current inks or do they need to run a spot color? Or, if they are running a spot color, can the proper color be achieved with the ink on press or do they need to clean the ink fountain and reformulate the ink being used?

The BestMatch function will help the press operator decide this very quickly. It will indicate how to adjust the ink to achieve optimum color match and the predicted results after the ink levels are adjusted. To use BestMatch, do the following:

  • First, measure the paper white.

  • Next, measure the target color (the color that needs to be achieved).

  • Highlight the “Sample” line on the display and measure the area being printed.

The display will now show the following information:

  • The peak absorbency of the ink measured (in wavelengths of light, nanometers)

  • The recommended correction, as a change of density (+ or -) or as a percentage

  • The current difference from the target color and the calculated best difference after the correction.

This function can be an invaluable tool to the pressman during color matches. It is simple to use and understand and can save valuable time by identifying an ink that will never meet color match or quickly provide the information necessary to adjust the press to achieve it.


Patch / Aperture Size requirements

Maximal Aperture Size Recommendation

  Spot Mode Scan Mode
Patch Size Spot only*
(max aperture size)
Strips < 10cm/4"
(max aperture size)
Strips 10cm/4" to 75cm/30"
(max aperture size)
Strips > 75cm/30"
(max aperture size)
2mm 1.5mm - - -
3mm 2mm 1.5mm - -
4mm 2mm 2mm 2mm -
5mm 4mm 2mm 2mm 2mm
6mm 4mm 4mm 4mm 2mm
7mm 6mm 4mm 4mm 4mm
8mm 6mm 6mm 6mm 4mm
>= 9mm 6mm 6mm 6mm 6mm

* For spot readings, it is always recommended to use the largest aperture size possible.  If the instrument is used for scanning as well, scan mode will dictate the aperture size.

Aperture Specifications

Aperture Size Measurement
area size
Opening in
target window**
Opening in scan chassis target window Screening Range
1.5mm 1.5mm 3.5mm 4.0mm 175 lines/inch or 69 lines/cm or above
2mm 2.0mm 4.0mm 4.5mm 133 lines/inch or 52 lines/cm or above
4mm 4.0mm 6.0mm 6.5mm 65 lines/inch or 26 lines/cm or above
6mm 6.0mm 8.0mm 8.5mm  

** For each eXact aperture size, the target window size is 1 mm (on radius) larger than the spot measurement area size. This 1 mm over iluumination of the measurement area is required by ISO5/4. The white area around the patch, does not influence the measurement data, but does require the operator to center the measurement sample in the target window opening.

The illustration below shows how this minimum measurement area appears in relation to the target window opening.

The black circle represents the target window opening.

The white circle represents the actual measurement area (which equals the aperture size).

The magenta square represents the minimum suggested patch size.

This can be used as a guide for operators when placing the instrument optics over patches which do not completely fill the target window opening.


eXact Aperture Sizes


M0, M1, M2, and M3 measurement conditions:

Please click the link below for a PDF file explaining the M0, M1, M2, and M3 measurement conditions used in the X-Rite eXact models.

The "M Factor"