ColorByte Software

Review of ImagePrint

The Virtual RIP

By Ian Lyons

A Computer Darkroom Review

As part of my Photo 2100 inkjet printer review I commented that compared to earlier models Epson had done a remarkable job with gray scale neutrality and color rendering. Even so some scope for further improvement remained with custom ICC media profiles in lieu of those supplied by Epson being the most common. I also mentioned that I was seeing very significant improvements in color and B&W by substituting the Epson driver with a RIP called ImagePrint from ColorByte Software. The following page contains my thoughts on ImagePrint for Mac OS X and is followed by a comparison between the Epson driver and ImagePrint.

So what is ImagePrint?

What it isn't is a substitute for Photoshop or any other image/graphic editing application; Photoshop, Illustrator, Corel Draw, et al are all safe. ImagePrint is a high performance print engine or RIP (Raster Image Processor) that has been designed to optimally convert image data into a format that can be easily interpreted by the printer. RIPS's are intended to process large quantities of image data very quickly and in this context a 100MB plus multi-layer image will typically begin to print after only a few 10's of seconds. In effect it replaces the conventional print driver with which we are all familiar. Furthermore, and unlike the majority of currently available RIP's ImagePrint was written to address the needs of the professional photographer rather than simply adhering to convention and dealing with the purely illustrative graphics market. The application was developed for, and is compatible with, a large range of wide bodied (Epson 7600, 9600, 10600, Fuji Roland, HP, IRIS, etc) printers. A LITE version or ImagePrint is available exclusively for the desktop printers listed below:

• Epson 1270/1280/1290

• Epson 2000P

• Epson 2100/2200

The LITE version of ImagePrint does not include the color correction, package printing, auto-print or page tiling features described in the ColorByte product literature. Nevertheless, for those requiring them the full feature set is available at additional cost. A demo version is available from ColorByte Software although at time of writing this review it was only available upon request. In order for ImagePrint to be fully functional it will need a spare USB port on your computer to accommodate the software protection dongle. Without this dongle ImagePrint will operate in demonstration mode; i.e. watermarking all images with the word "Demo".

Depending on the printer make and model ImagePrint supports various print speed (quality) and media sizes including all the standard options from the Epson driver. For example, with the Epson 2100/2200 this includes 720dpi, 1440dpi normal and high speed printing plus 2880dpi printing. Multi-pass printing is also available for printers such as the Epson 7600/9600.

The main ImagePrint application is also the control centre for laying out images and sending them to an output device such as an inkjet printer. ImagePrint provides a large assortment of high-end layout and color correction tools although as noted above some of these have been omitted from the LITE version. ImagePrint is designed to be extremely easy to use with visual feedback provided for virtually every feature. This means that you can achieve true WYSIWYP (What You See Is What You Print) output without sacrificing the power of a high-end printing application. ImagePrint is a fully cross-platform inkjet printing solution that should be equally competent in any Windows, Macintosh or mixed network environment. However, for optimum printer performance on mixed networks ColorByte recommend a multi-tasking operating system such as Windows 2000, XP or OS X.

The screen shot shown below shows the main tool palette and control panel (all of which can be hidden if required). Unlike applications such as Photoshop the image displayed in the Layout Area is a Softproof which means it is previewed using the active media profile rather than the more conventional working space profile. This can be a bit disconcerting at first especially if a matte paper has been selected, but you soon get used to it.

ImagePrint Interface and Tools

ImagePrint is suitable for printing both Bitmap and Vector based images; a Postscript option is also available. You'll only need the PostScript version if you print PDF or EPS files, or would like to print directly from within any Windows application such as Adobe Illustrator, InDesign or Photoshop.

As befits any application claiming to be a RIP ImagePrint facilitates automatic page layout. It allows the user to simply drop images onto ImagePrint and these are then automatically positioned on the page. If you want to move an image just drag it into position using the fully WYSIWYG enabled page composition controls. User defined page sizes can be saved and called back for use at any time using a dedicated dialog. To configure a new page size it's simply a matter of specifying the actual page dimensions and ImagePrint will take care of the rest. The following screen shot shows an example for A3 paper.

ImagePrint also supports roll paper and so those wishing to print panorama images can do so without resorting to stitching prints together. I haven't established the actual maximum print length but am advised that it exceeds any roll media supplied by Epson.

20 April 2003

With the introduction of ImagePrint 5.5 ColorByte have delivered some new and very welcome enhancements. After overcoming a few hurdles (the beta version I was testing wouldn't recognise my Epson 2100) I finally got down to putting version 5.5 through its paces. Image Centring and True Borderless Printing are now possible. The image centring feature places the image centrally relative to the actual page size rather than the more normal printable area, which is a welcome improvement on Epson's definition of centre. The absence of Borderless Printing wasn't something that I spilled many tears over but it's now available and appears to function as advertised. The following screen shot shows the dialog where the user activates these features. Media Type and Feed Adjustment are only available on the Epson 7600/9600/10600 printers.

Centre Margin and Borderless Printing

The package print feature gives the professional photographer a fair degree of flexibility. A different template can be applied to every image on the page and Templates can be designed to any size with as many frames as your page size can accommodate. Set-up the frame orientation in either landscape or portrait to maximize page use and let the Auto-Rotate feature take care of the rest. Images will be rotated automatically to fit the frame size.

ImagePrint support for Templates

ColorByte ImagePrint - Gray Scale Color Management

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 color management features in the printer driver turned off.  To turn color management off in any Epson printer driver you simply choose No Color Adjustment mode. Prints made using this mode  tend to look dark and have a strong color 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 colored 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 colored 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 color 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 color 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 color channels cross each other (crossover) and compare them with Figure 1. Notice that once No Color 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 color cross-over, posterisation and banding, albeit not as evident with the Photo 2100 as it has been with earlier models. Color 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 color 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 color gamut along with very smooth gradients in both color and grayscale.

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

Color Gamut

In Figure 5 below you can see clearly the trade-offs in color 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 color 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 color gamut has been significantly reduced.

Figure 5 - Comparing the Color 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.