QuadToneProfiler QuickCurve for macOS Instructions

Introduction

The new QuickCurve for inkjet prints using the Epson UltraChrome K3 printers, including the new series of Sure Color printers, allows for easier profile creation, toning variations and blends, and linearization without the need to go through the traditional QuadTone RIP profiling process.

This new app will also blend any two quad files from the same printer model, and linearize any existing .quad file from a positive print. This makes it compatible with all Piezography, PiezoPro, and PiezoDN curves.

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Requirements

This method requires macOS 10.11 or later (El Capitan through Mojave)

QuadToneRIP on macOS (or older versions of OS X)

Measurement device and software or a flatbed scanner with Photoshop and the QTR-Stepwedge Tool

Measurement Devices and Software

X-Rite i1 Profiler, ColorPort, and ColorMunki, and DataColor SpyderPrint

This workflow is based on measuring the patches from a number of standard step wedge targets. The method used with my system works best when measuring with automated chart readers or handheld spectrophotometers capable of measuring in strip mode, however it is possible to use a manual densitometer or scanner and a Photoshop color picker to manually record the measurements.

There are free versions of these Xrite programs and the demo modes are suitable for the chart measurement steps. There are slight differences in how these programs work and I have written or can provide additional instructions as needed. Both programs have their own benefits and drawbacks, and your measurement device and operating system, along with your personal preference, will determine what program you use.

Basic Interface

The application is divided into three tabs: Starter Curve Setup (above), Toner Curve Blending, and Linearization.

The QuickCurve Starter Curve Setup has predefined ink levels for the three black inks for gloss and matte papers for the UCK3 printer families, and are compatible with the Stylus Pro UltraChrome K3 and new Sure Color K3 printers. All papers and printers are different so there are additional options to customize the total ink load and the ink levels for the six standard toning curves, as well as make custom toner settings.

If you using Piezography systems you will only be using the Blending and Linearization features.

Step by Step Instructions

Starter Curve Setup Workflow Overview

  • Choose the printer model and paper type
  • Choose K3 as the Toner Setting
  • Set the ink limit for that paper
  • Save the current K3 starter curve to the QuadToneRIP/Profiles/yourPrinter folder
  • Choose any of the other toner settings save the current starter curve with the toner settings to the same folder (the K3 inks will be lowered based on the amount of color ink used—do not readjust the ink limit slider back up to the K3 toner setting levels)
  • Double-click the installprinter.command file to install the new curves.

Naming the Curves

The curve name should be the paper make and type, as well as the initial black ink limit. My standard approach is to put the paper manufacturer first so they show up together in the list of available curves in the QTR curve dropdown menu.

For Hahnemühle Photo Rag I would use Hahn-PhotoRag-K72 or Hahn-PRB-K72 for Hahnemühle Photo Rag Baryta (the 72 refers to the starting black ink limit)

For Museo papers I might use something like MusSilverRag-K72 or MusPortRag-MK80 (the MK to designate matte black in cases where it might not be obvious)

There is a 37 character limit for QTR files names so you might need to come up with your own abbreviations.

Setting Your Total Ink Limit

The curves are made with preset black ink limit for that printer. These were chosen because they produce a rich dark black on high quality glossy or matte papers and still allows for easier linearization. You can change the ink limit by moving the slider until the value displayed reaches the setting you want. There is a bug that will let the ink limit go past 100% with certain paper and printer combinations. If this happens, simply move the slider to the left until it goes under 100.

Lower quality papers (and uncoated or specialty papers like kozo) might not be able to handle the higher ink load in the standard starter curves. You can use the slider to lower the black ink limit to prevent pooling or excessive bleeding for that paper. The number displayed is the result of several behind the scenes calculations and it isn’t possible to manually type in the ink limit.

The addition of the toning inks will increase the total ink load, and you will notice the black ink limit will go up or down based on the level of toning inks added. The recommended practice is to first set the black ink limit for using the K3 inks only, and not change it for that paper for each of the toning curves. This will produce a similar Dmax for each of the toning curves, and will allow for easier curve blending in the QuadToneRIP print dialog box.

Saving and Installing the Base K3 Curves and Toning Curves

Once you set the base black ink limit you can save the curves containing only the K3 inks that can be useful in blending with the other toning curves in the QTR print dialog box.

The Base K3 starter curves were pre-linearized and smoothed for compatibility with most high quality gloss papers, but they should be linearized for each paper and printer for the best results.

Using the Standard Toning Settings

The drop down menu for the toner ink controls will preload the toning recipes for each of the standard print hues.

You can edit the toning profile for the drop down selection by changing the saturation slider. That will simply decrease the amount of color inks for the whole scale. Then press the button to save the starter curve and name it the same as you did the K3 file, but you will also need to manually add the name or “code” for the toning recipe.

Toning Recipe Codes

The toning codes are as follows:

Se Cool Selenium (slightly purple)

Cl Cool Blue (slightly blue)

Nt Neutral

WN Warm Neutral

Wm Warm (slight reddish yellow)

Sp Sepia (heavy reddish brown)

Neutral Curves

The neutral toning curve was designed after testing many different ink recipes using my own gray balancing formulas. I used a paper with a very neutral base to balance the warm yellow/green of the Epson K3 inks with a proportion of light cyan and light magenta inks. With the exception of the neutral profile, all of the other ink recipes can be modified with the the individual C and M settings.

Installing the Starter Curves

On macOS you will need to save or move the exported .quad files to the Applications/ QuadToneRIP/Profiles/(yourPrinter) folder and run the install command in that folder.

Linearization

Linearization Workflow Overview

  • Print the stepwedge target with the number of patches you want to use with the .quad curve to linearize in the Curve 1 dropdown menu in the QTR print dialog options
  • Measure the target from white to black and save the LAB data
  • Go to the linearization tab in the QuadToneProfiler application and open the measurement data file (or open and save it in QTR Data Tool and save and reopen the .txt file in the QuadToneProfiler app)
  • Open the .quad file used to print the target in the QuadToneProfiler app.
  • Adjust the smoothing settings so that there are no bad bumps in the measurement data or the linearized quad curve graphs.
  • Save the linearized quad file and add “-LIN” to the file name to the QuadToneRIP/Profiles/yourPrinter folder
  • Repeat for all the toning profiles and then run the install command
  • Print a 21-step target and test image with each of the toning curves to confirm linearity and to use as a guide for the curve blending

Linearization in Detail

The addition of the toning inks will require each one to be linearized before being used by itself or blended in the QTR print dialog options.

Linearization can be done with step wedges with 21, 51, 86, 128, 129, and 256 steps and measured with a densitometer or photospectrometer like an i1Pro, ColorMunki, or SpyderPrint.

The application supports measurement files made with all the common devices and measurement formats including: CGATS, DataTool.txt, QTR-LinearizeData-out.txt, QTR-Stepwedge-Tool.txt, ColorMunki.csv, SpyderPrint.txt files

The easiest way to do this is to export the Base K3 and each of the six toning profiles and use the included 21-step minimal grayscale target. When using QTR Print Tool for macOS, all 7 targets can be printed on half a letter sized piece of paper. Each target is measured one after another, and then the linearization information can be pasted in and the final curves exported one after another in quick secession.

Printing the Targets

Open Print Tool on macOS and load the step wedge target. Position the first target about 3/4–1” from the top of the page. After each printing you can simply march it down the page and print using the next toning profile, leaving about 1/4” to 1/2” between each target.

Make sure you choose no color management in the Print Tool color management options. Windows QTRgui users do not need to worry about color management when printing this target, as long as it was not open in Photoshop or had and embedded ICC profile assigned or changed.

Choose the first set of quad curves using the Base k3 inks only from the Curve 1 dropdown menu in the QTR print dialog. Leave the other two curve dropdown menus blank. I recommend using 16-bit printing on macOS.

Make sure you are using the correct paper feed, unidirectional print speed, and 2880 dpi for the printer resolution and print the target.

Then move then image down in the page layout window or change the top margin to move it under the previously printed target and choose the next toning curve to print in the Curve 1 dropdown menu and print the target again. You will need to repeat this process for each of the toning profiles you want to linearize for that paper, and then again for each other paper you wish to profile.

If you are profiling multiple papers you should only need to export one set of starter curves (unless the papers have much different paper base colors to neutralize or cannot handle the same ink loads). You would then simply use the same set of starter curves to print each of the targets on all the papers. The only thing to change is the curve name when pasting in the measurement data for each paper before exporting the final linearized curves.

Measuring the Targets

I recommend force air drying for a few minutes or letting the inks cure for several hours before measuring to be sure to get an accurate set of measurements for the final linearization. I also recommend taking an average from three or four samples from each patch to minimize the risk of bumps in the curve from measurement errors. That is easier with a 21-step target, but can take extra time with manual measurements from larger patch sets.

Measure the targets made with each of the toning curves and save each set of measurements in their own text file, being sure to name the file with the name of the paper or starter curve name and toner profile code.

Data Averaging and Smoothing

Measurement files with multiple samples per step are automatically detected and averaged when the file is opened.

Measurements will usually have some degree of noise that can cause spike or bumps in the linearization. You can use the two smoothing sliders to smooth the noisy data.

The original measurement data is interpolated to 256 steps for the actual linearization calculations. The black dots are the interpolated data and the red line is the data that is actually used in the calculations. The black dots show ever other interpolated point. Over-smoothing can lead to unexpected and unwanted results so the goal of the smoothing is to make the red line smooth while still tracking to the overall trend in the original data.

Smoothing Slider 1:

The top smoothing slider sets a window size for a moving average on the number of interpolated points.

Measurements from smaller targets like 21 or 51 steps will require a lower setting than larger targets. The differences between 1-5 points are not noticeable unless the data is very noisy and there are some values that disproportionally cahnge the shape of the curve.

The values from this smoothing option are then used for the calculations in the lower smoothing setting. The original unsmoothed values are used if the smoothing 1 slider is set to 0.

Smoothing Slider 2:

The bottom smoothing slider controls a smoothing method that takes a percentage of the total number of points from the moving average values and resamples a new set of 256 points that are then used in the linearization calculations.

There is a default smoothing setting when a new curve is loaded, and to remove the default, move the slider to the right and then all the way back to the left so it reads as 0. As you move to the right, it will get enough points to calculate the new curve, and will keep adding points until it gathers 1/3 of the points. So as you move the slider to the right, it will map closer to the original values from the moving average.

In most cases, it is best to use some combination of the two smoothing controls. When using smoothing 1 only, higher values can adversely affect the shadow tones. Very low smoothing 2 values can exaggerate the curve at the highlight end of the scale.

Smoothing for Digital Negatives

PiezoDN or Gravure users: There will be more noise in measurements from darkroom and hand coated processes that will require larger patch sets and higher smoothing values.

Creating the Linearized Curves

Choosing the linearization method

There are two options for the linearization output curve. The first is for linear Lab L* with evenly spaced Lab L* values for each of the measured steps. The second option is to define a specific output curve to map the linearized values to. The linear Lab L* is usually advisable for most gloss papers, but the modified density curve can be helpful for offsetting the weak feeling in the shadows from matte papers.

The argument for using the manual density curve for gloss papers is that the highlights and upper midtones of gloss papers might appear too dark depending on the total Dmax of the paper and ink combination.

In either case you choose, make sure each of the toning curves is linearized to the same target density curve.

A good starting point for manual density curves for Gloss papers is:

Shadows: Input: 95

Output: 96

Midtones: Input: 70

Output: 71

Highlights: Input: 5

Output: 4

A good starting point for manual density curves for Matte papers is:

Shadows: Input: 95

Output: 97.5

Midtones: Input: 60

Output: 62

Highlights: Input: 10

Output: 10

Exporting and Installing the Final Quad Files

When all the toning profiles are created you will need to move or copy the linearized curves to the quad printer folder for your printer.

On macOS you can simply move them to the Applications/ QuadToneRIP/Prifiles/(yourPrinterFolder) and run the install command. That will copy the .quad curves to the Library/Printers/qtr/quadtone/(Quadprinter) folder and make them available for printing in the QTR print dialog box.

Confirming Linearity

To ensure the new linearized curve is printing correctly, make a test print of your standard test image or the bullseye gradient torture test included in the Resources folder. This will show any obvious reversals or problems with the linearization. If there are linearization problems please send a support email and include the starter curve and the measurement data that was used for the linearization.

Curve Blending

One of the most powerful aspects of QuadToneRIP is the curve blending option in the print dialog window. I created a built-in blending option with more control points and a preview of the blended curves. It also allows you to use graphs of the measured linearization targets as a guide for how much of each curve to use for different parts of the scale.

Needless to say the toning settings are going to be a largely personal decision, but one you arrive at a toning blend you like you can save that as a QTR QuadPrinter preset to use again and again or modify slightly for images with different tonal qualities.

Curve Blending Workflow Overview

Curve Blending should be done from the measurements of the linearized curves.

  • Open QuadToneRIP Data Tool application and open the measurements from the K3 curve and the toning ink curve to blend to graph the a* and b* values for the two curves.
  • Go to the QuadToneProfiler’s Curve Blending window Open the linearized K3 as Curve 1 and the one to blend as Curve 2.
  • Use the graphs of the a* and b* values and adjust the curve blend percentage to arrive at the desired a* and b* print hue.
  • Save the new blend with a unique name to the QuadToneRIP/Profiles/yourPrinter folder and run the install command.
  • The blend percentages for each point will be saved as a notes comment in the .quad curve header information and can then be viewed in a plain test editor or the QuadToneProfiler linearization notes field.

Toning Recipes

The premade toning recipes will be a good staring point for customizing to suit you needs, but the information below might be helpful in understanding what ratios for the CMY inks produce what toning hues.

Neutral

A close neutral approximation can be made with a ratio of 3 parts Cyan to 4 parts Magenta (with individual levels between 6-12)

Warm Tone

The base K3 ink are a warm yellow that can take on a light green appearance. A better warm mix is to use 2-5% magenta to offset the green appearance of the Base K3 inks. A very low percentage of yellow can be added as well

Cool Tone

Similar levels of Cyan and Magenta can be used in combination at about 1:1 to arrive at a cool blue appearance when using individual levels between 10-20)

Selenium Tone

A selenium tone can be achieved by higher levels of Cyan and Magenta (with individual levels between 10-20) at a ratio of about 3 parts Cyan to 5 parts Magenta

Sepia Tone

The “sepia” toned curves are extremely warm and care is needed when using the yellow channel to prevent premature fading and to minimize the risk of arriving at an orange toned print. A good starting point is to use a mix of magenta and yellow at a ratio 5:1. Most of the yellow will come from the Base K3 curves, and is enhanced by the yellow ink and the red from the combination of the yellow in the base K3 inks and the added magenta inks. The sepia curve alone is often too warm for most uses, but can add a nice effect when blended in small amounts with in the QTR print dialog or included curve blending options.