The following screenshots are provided so that you can compare the gray balance of ICC profiles for the Epson driver when using "No Color Adjustment" mode with the equivalent mode in the ColorByte ImagePrint driver. However, in order that we can actually make the comparison I first needed to print and then measure a special profiling target comprising multiple patches with known RGB value for each patch. In the case of the Epson driver this is done with all colour management features in the printer driver turned off.  To turn colour management off in any Epson printer driver you simply choose No Colour Adjustment mode. Prints made using this mode  tend to look dark and have a strong colour bias (usually green).

Before looking at the results for my No Color Adjustment tests I must first check the linearity of the printer output as produced when the driver is set to more common print modes such as PhotoRealistic or ICM. In the screenshot labelled Figure 1 the heavy black diagonal line depicts a linear relationship between the Input and Output RGB values. By linear I mean that for an input value of 1 we get an output of 1, for input of 10 we get an output of 10 and so on - R=G=B=Neutral. The three coloured lines are the compensation curves needed to linearise the actual printer output. Since the curves sweep below the diagonal we can also determine that the correction required to linearise the output will in the main darken the image slightly.

Also notice that the three coloured channels deviate from  the black diagonal by only a small amount. From figure 1 we can clearly see that  the Epson printer and driver combination should be capable of producing very good grayscale with virtually no colour cross-over.

 

 

 

Figure 1 - Gray Balance for Photo 2100 in PhotoRealistic mode

 

So if the Epson driver in PhotoRealistic or ICM mode is so good why do we bother using or even creating custom media profiles? A good question and one that doesn't have a simple answer. Furthermore this discussion isn't intended to provide the answer except to say that in obtaining such linear output Epson made some very significant compromises which resulted in the loss of a lot of the colour gamut that the Photo 2100/2200 is capable of reproducing.

So let's get back to ImagePrint and the more conventional method of profiling an Epson inkjet printer. Figure 2 represents the  relationship between the greyscale Input and Output values for Epson's own generic Epson Premium Semi Gloss paper profile. Particular attention should be paid to the various points at which the colour channels cross each other (crossover) and compare them with Figure 1. Notice that once No Colour Adjustment mode is selected in the Epson driver all semblance of linearity disappears. A print made using this mode but leaving out the profile will be truly horrid in appearance; being dark and very likely green. The gradient of the curve at the shadow-end (bottom left) is initially quite steep and then abruptly becomes less so. This area of the curve shows the extent to which the input data must be compensated in order that the shadows are rendered correctly. Unfortunately such crude corrections often tend to result in colour cross-over, posterisation and banding, albeit not as evident with the Photo 2100 as it has been with earlier models. Colour cross-over can be very obvious when printing monochrome images.

 

Figure 2 - Generic Epson Premium Semi Gloss Profile

 

Figure 3 reproduces the relationship between the greyscale Input and Output values for my Photo 2100/2200 printer using the same media type, i.e. Epson Premium Semi Gloss photo paper but this time based on a custom created profile. The measurements were made using Gretag Macbeth i1 Spectrophotometer and recorded in the measure module of ProfileMaker Pro 4.15. Note that whilst the shape of the curve for each colour channel is broadly similar to the generic Epson profile it is sufficiently different that quite significant improvements in the neutrality of grayscale prints can be obtained on my printer. Even so it is nowhere near as good as I achieved using PhotoRealistic mode.

 

 Figure 3 - Epson Driver Gray Balance for the 2100 Photo Printer

 

Figure 4 depicts the printer in same condition or mode as Figures 2 and 3 but this time using a profile built for ColorByte ImagePrint 5 RIP. Notice the shape of the curve is entirely different from the previous examples and that crossover is virtually non existent. The curve is gradual and relatively smooth, and so avoids the potential for posterising and banding. Leaving aside the fact that the tone-curve is the opposite of that shown in Figure 1 ColorByte seem to have managed to get the raw output from the Photo 2100/2200 nearly as good as Epson did in their highly tuned and corrected Automatic/ICM mode. ColorByte Software have done so whilst also ensuring that the output retains a wide colour gamut along with very smooth gradients in both colour and grayscale.

 

Figure 4 - ColorByte ImagePrint 5 Gray Balance for the Photo 2100 Printer

 

Colour Gamut

In Figure 5 below you can see clearly the trade-offs in colour gamut that occur when trying to optimise the gray balance of the printer. The Epson driver custom profile was built with the driver set to No Color Adjustment mode and corresponds with the gray balance graph shown in Figure 3. The ImagePrint custom profile (Figure 4) has a marginally smaller colour gamut but gray balance is excellent. Whilst I haven't shown it in the screenshot profiling the printer in Epson's PhotoRealistic mode results in the colour gamut has been significantly reduced.

 

Figure 5 - Comparing the Colour Gamut

 

Conclusion

This has been a very simplified explanation of why profiling the printer doesn't necessarily mean that the result will be a near perfect grayscale. It should also be obvious from the screen shots that in developing their own driver for mass usage in PhotoRealistic mode Epson haven't spent anywhere near as much time or energy optimising the greyscale output for custom media profiles. This means that those wanting to get the best out of a printer such as the Photo 2100/2200 will need to look beyond the Epson driver for a solution - the solution I chose  is ColorByte ImagePrint.