## General QuadToneRIP Information Make sure QuadToneRIP is installed and you have a basic familiarity of the user interface. I realize there is usually a rather steep learning curve for people just getting started and some of the QuadToneRIP specific terms can be early stumbling blocks for people. Before diving into the actual workflow, I think it would be best to clarify some of the often confused terms that are used in the profiling process. This first and most important is the word "profile" itself. ### QuadTone RIP Profiles and ICC Profiles #### A QTR profile **is not** an ICC profile. One of the largest sources of confusion is the multiple usages of *profile*, especially for people accustomed to using a standard color managed workflow with the OEM printer driver. Thankfully, Color Management is not as intimidating or confusing as it was when ink jet printers and digital photography was starting to gain in popularity.Now most photographers using inkjet printers have a good handle on using a color managed workflow by defining an ICC Profile for their paper and printer when printing through Photoshop, Lightroom, or their other favorite image editors. Unfortunately, that can lead to problems when they start using QuadToneRIP. Many problems and points of confusion are introduced when people are not clear about how they use the word *profile*. It is a good habit to specify if you are referring to an ICC Profile or a QTR Profile—especially since you can use a custom ICC Profile when printing with a custom QTR Profile for a black and white color-managed workflow… (see confusing!). It can be helpful to think about QTR Profiles as containers for the information needed to construct a*media settings* for a paper, printer, and ink combination. So then you color manage right? Well, yes, but you shouldn’t. Color Management with QTR and black and white ICC profiles is a sticky subject that is best to just ignore for now. My particular view is that the whole point of the QTR calibration process is to make custom media settings so there is less need for ICC profiles to correct for problems with the printer. Matching it to the display is a whole other can of sardines. ### Basic QTR Terminology Now that "profile" has been cleared up there are a few terms that need to be understood before diving into profiling. This is not meant to make you a QTR expert, but here is a short crash course. If you have been using QTR and making your own custom profiles you can skip to the step by step instructions and just refer back to this if needed. #### QTRgui.exe The QTRgui is the stand along image layout and QuadToneRIP printer driver used with Windows. It is the graphical user interface that contains the curve creation tools for creating, opening, and editing ink descriptor files (.qidf files or profiles). The QTRgui has its own advantages and disadvantages over the text-based ink descriptor files, but is the only option for using QuadToneRip on a Windows PC. #### .qidf and .txt Ink Descriptor Files — QTR Profiles This version of QuadToneProfiler—DN is designed to work independently of the QIDF text file, but I include information about it here for clarity. The files ending in either .qidf or .txt are plain text files that hold the instructions the QTR Curve Creation Algorithms uses to create the overlapping gray inks and toner partitions. On Windows, the .qidf files are created by typing text inputs into the boxes in the QTRgui curve creation module, but they can just as easily be created and edited in a basic plain text editor. #### .Quad files — QTR Curves The Quad curves are the final result of installing the the .qidf/.txt file profiles when using the QTR-curve creation program or what are exported from the QuadToneProfiler apps. The Quad curves can also be thought of as the media settings you select in the QuadToneRIP driver in the curves menu. Behind the scenes, the .quad files are simply unsigned 16-bit integers that signify the ink level for each of the 256 steps in the grayscale. These files are not directly edible with the standard QTR curve creation tools, but there are a few different methods of editing the ink levels. That is beyond the scope of this document, but the tools included in the QuadToneProfiler Deluxe edition can be used to load, edit, and export .quad files. #### Print Tool.app Print Tool for Mac OS X allows you to layout multiple images or multiples copies of one image on a single page. This is not exclusive to printing with QuadToneRIP and can be used for any installed printer on the system. PrintTool is integral to the profiling process because it allows the user to bypass OS X's and Photoshop's color management settings for printing the Ink Calibration Image files and the grayscale targets used in the profile creation process. Adobe Color Printer Utility has this ability to bypass the system’s color management, but does not have the ability to control the layout of multiple images on one page. Print Tool also allows for easy color managed printing and soft-proofing with any installed ICC Profile. #### Curve Creation Curve creation is one of those confusing terms and it can mean “create a correction curve” to match the native output to a defined target. This is more often used by with people making digital negatives, but is a case where further clarification is needed. Curve Creation can also be a reference to the behind the scenes functions that partition each ink channel into the smooth overlapping segments seen in the final .quad file. This second usage of curve creation is generally how I use the term, and I will specify “create a correction curve” for the linearization steps. #### Linearization Linearization will be covered in more detail in the step by step instructions, but basically it means: measure the native output from the printer and generate a correction curve to produce a standardized evenly distributed output densities. The problem with “linearization” is that different measurement formats represent density differently and linear Density might not be linear L\*a\*b\* L\* . In general QuadToneRIP terms, Linearization means make the L\*a\*b\* L\* measurements evenly spaced from the paper white to the darkest printable tone. When it is graphed it looks like a straight line. There is a lot of debate on whether this is the ideal way of doing things, but it is a good reliable standard and an easy one correct to. ### QuadTone RIP Profiles and QuadTone RIP Curves ***QTR Profiles*** and ***QTR Curves*** are often used interchangeably when discussing QuadToneRip, which leads to some of the natural confusion for those first diving into creating custom settings for their printers and papers. That confusion can also lead to problems when trying to trouble-shoot problems or participate in online discussions about the profile creation process. A QTR Profile is often used as generic term for a file that contains all the settings for each paper, printer, and ink set, and toner settings. The problem is that *profile* can have different meanings depending on the context in which it is used. When used generically like this it can mean both to the text file that contains the user inputs used to generate .quad file, as well as the .quad file itself. I will attempt to dispel some of that ambiguity by redefining how those terms are used throughout the calibrating and profiling process—don't worry if you find yourself confused at this point; the next few sections should shed some light on this #### .qidf and .txt files — QTR Profiles or Ink Descriptor Files The **Quad Ink Descriptor File** is simply a plain text file with a special extension that allows it to work with the Windows QTRgui. You can open these in Notepad on Windows by right clicking and choosing to “Open with” note pad. These .qidf files can be used on OS X, but you will need to define an application to open them. If you are working on OS X then simply save them as .txt files, and carry on. These *ink descriptor files* can be thought of ink recipes, and hold the instructions that a series of functions in the *QTR Profile Installation Script* will use to create the overlapping gray ink and toner partitions. *Profile* might not be the best word for these ink descriptor files, but they are located within the *Profiles* folder in the QuadToneRip application folder, and . In thinking about the definition of profile—information about the characteristics of something (in this case, how the inks are partitioned in the .quad file)—it is fitting, but it can lead to confusion when not preceded with *QTR*. ### QTR Profile Installation Script I’ve referenced the QTR Profile Installation Script or Curve Creation Program several time already. It is ok to not care *how* it works, but it is a good idea to have a basic understanding of what it is, how to use it. #### Installing the Profile/Curves You have to options for loading a new profile or a new set of curves on macOS. The first is to rerun the InstallPrinter.command in the profile folder that you ran to create the QUADxxxx printer and print queue (if connected by USB)). When you double click the install.command file you will see the profile install script run (quickly) in a Terminal window. This installation script is a command line tool that automatically processes all of the plain text quad ink descriptor files located in that profiles folder (if there are any). The end result of running the install script is a text file with a .quad extension that contains the 16-bit values for each of the 256 steps of the grayscale for each different ink channel. The install script doesn't change or save anything in ink descriptor file. It looks to see if there is an existing quad file in the library/printers/qtr/profile/quadxxxx folder (or the equivalent on a PC). If a quad file with that name does not exist, it builds a new quad file and creates a set of curves based on the instructions in the qdif file. If there is an existing quad file of the same name, it rewrites the set of ink curves based on the instructions in the qdif file. Those inputs in the qdif files might be exactly the same every time, but since the script doesn't "know" if anything is different in the .quad or ink descriptor file it recreates the ink curves overtime it is run. If you are on macOS and have installed final version of the linearized qdif file you can remove it from the profiles folder in the QuadToneRip applications folder. If you remove the qidf file from the profiles folder it won't rebuild the quad file every time the install script is run, but you will still be able to print with that set of quad curves. It isn't important, but it might save a few seconds each time you run it. You can remove all the profiles for papers that you are not going to use (and remove the .quad files from their respective folders too). That just helps keep the print dialog boxes a little less cluttered and less searching for the curves you really want to use. ### The .QUAD File If you were too look at the .quad file in a plain text editor, you will see something link this: Numbers ranging from 0-65535 on hundreds (or thousands) of separate lines, depending on the number of inks used in that model printer. `## QuadToneRIP K,C,M,Y,LC,LM` `# QuadProfile Version 2.7.5.0` `# K curve` `0` `0` `0` `0` What these numbers actually represent are the 16-bit (unsigned—neither positive or negative) integers that control the amount of ink at each of the 256 steps that make up an 8-bit tonal scale. These 16-bit numbers are the percentage of the total ink the printer is capable of spraying onto the paper at any given point. 0 is 0% ink, and 65565 is 100%. Fortunately, these values are created by the QTR installer script, and we do not need to make the calculations ourselves to create the quad value for each ink for each of the 256 steps. Our job in the profile creation process is to give accurate instructions that the QTR installer will use to do this work for us. ### Accessing to Your QTR Profiles and Quad Curves Now that you know some of the terminology, we can start to dive into where to find these different kinds of files. There are two folders associated with each printer. One for the Ink Descriptor Files (QTR Profiles) and one for the .quad files (QTR Curves). You can put your .quad curves that are exported from QuadToneProfiler directly into the curves folder or the profiles folder. The .quad curves in the profiles folder will be copied to the curves folder when you run the install command. These are in different locations on Macs and PCs, but the folders are similarly named. PC users can access the Ink Descriptor Files through the QTRgui curve creation module. QTR Profiles (ink descriptor files) are not used with my QuadToneProfiler apps, but are located in folders organized by printer model and ink set in the QuadToneRIP/Profiles folder. These are directly related to how the QTR curve (.quad file) folders are named and organized, but in reality, you can have the ink descriptor files located anywhere on your hard drive. ### Viewing the Quad Curves macOS X users access these files directly through the finder, and then can view the Quad curves in QTR CurveView. In macOS these .quad files are stored buried in the system library folder, so I recommend people create an alias to the QUAD printer folders on the desktop or as a favorite folder I the finder sidebar. Here is an example file path to find the .quad files: StartUpDisk/Library/Printers/QTR/quadtone/quadxxxx (ex: quad1430-K6 or quad3800-UC) There have been security updates to Windows that sometimes result in the Quad curves being written to: C:\Users\[your computer name]\AppData\Local\VirtualStore\Program Files (x86)\QuadToneRIP\QuadTone This is different than some of the existing QTR documentation that was written before these security settings were put in place. On Windows, there is no way of viewing more than one set of quad curves graphs at a time. If you simply want to view the graph you can right click on the curve name in the QTRgui and click “show curve”.