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Managing Image Color and Quality – Part two of two

The second part of this post on managing image color and quality focuses on the variables that are out of your control… and lucky you – under your printer’s control. I’ve tried to not get overly detailed about this technical stuff. There’s a line that we designers do not need to cross in our understanding of printing technology and I’ve tried to stay on the designer side. Having that said, I have never met a designer who was not interested in how graphic things work. And because of this experience and understanding of how designer’s minds work, I’ve included here the stuff that directly impacts you.

Things Your Printer Controls

Screening
This section assumes that your print provider is capable of AM and FM screening. (These two screening methods are defined in the following paragraph.) If your printer is not capable of both screening techniques or hybrid screening (which combines both on the same plate), and you are doing critical catalog, book, or annual report work, you need to find a printer that can handle those projects. This section also assumes that your printer’s prepress expertise allows her to adjust her plate curves for the substrate. (These are adjustments made in prepress to manipulate the halftone dot to create the optimum dot size for the job conditions.) These are not parameters you can send to your printer. Each pressroom adjusts its own settings, based on the equipment it has, to produce its best work. Between screening and other adjustments made in their prepress department, your printer makes sure that images print at the best possible representation of the file.

Conventional (AM) vs. Stochastic (FM) Screening Methods
In order to print an image via a printing press, of nearly any type, the image must be converted to a halftone; that is, the image must be made up of dots. There are two ways to convert the image to dots, and they are both referred to as “screening.” The older and more common method is conventional or AM screening. Conventional screening puts the dots in fixed rows, varies the size (Amplitude Modulation) of each dot, and places each ink color at a different angle. The second method is FM screening, and it scatters the dots at variable distances (Frequency Modulation). In FM screening (also called stochastic), the dots are a fixed size, but they are microdots (microdots are called spots). The two forms of FM screening include first order and second order. Stochastic is an example of first order FM screening, wherein the dot size is fixed and the frequency is variable. Second order FM screening allows for altering the dot size in areas where there is high density. Staccato (a Kodak product) is an example of second order FM screening.

AM screening varies the size of the dot while
keeping the distance fixed.

FM screening varies the distance between
spots and the size is fixed. 

Second-order FM screening varies the size and
distance between spots.

Your print provider can also vary the type of dot used; in addition to round dots, there are elliptical, diamond, linear, and square dots. A dot that is not round may be used to fine tune an image such as a photograph due to the effect the dot has on very small gradations. Your printer will choose the type of rosette and dot shape that is best for your job. It will depend on the paper, line frequency, type of press, and the characteristics of the images in the printed piece.

Whether your project is being screened with AM or FM, your printer will manage dot gain by adjusting the image in prepress for the type of paper you are printing on. Printers store characteristics for paper types and specific brands and finishes so that they do not have to re-key the information for each print job. When printing images with geometric patterns, such as fabrics with linear textures or repeating geometric backgrounds, all fm screening is superior. It’s random dot placement eliminates the interference that conventional screening produces when the angle of a line of dots intersects with the angle of a design element. This phenomenon is called a moiré, and it produces an undesirable ripple-like effect in the image.

Screen angles placed to produce a moiré

Conventional screen angles for CMYK and the resulting “rosette”.

Although nearly every digital prepress system is capable of producing stochastic screening, its adoption has lagged behind conventional screening because of the spot/microdot it generates. The spot is more difficult to proof and image on a printing plate. Only newer, higher-end platesetters can image a microdot. Some high-end prepress systems are able to generate hybrid screening, which is the use of FM and AM screening on the same plate. Therefore, FM screening can be used for a difficult fabric pattern and AM for the text so that each image type is reproduced with the more advantageous type of screening. The AM and FM screening methods each have their own advantages and disadvantages.

Advantages of AM Screening
• Easier to make adjustments on press
• Clean, perfect screen tints

Disadvantages of AM Screening
• Patterns can cause moiré in screening.
• The background/paper color shows through more, which affects the overall color more than with FM screening.

Advantages of FM Screening
• FM is better for touch plates printing together with AM CMYK (as in Hi-Fidelity printing)
• FM is more forgiving of mis-registration, which is an advantage when printing across the grain and dealing with paper stretch.
• Larger CMYK gamut may be possible depending on paper choice
• Better reproduction of geometric patterns
• Less dot gain with the microdot of stochastic/FM screening.

Disadvantages of FM Screening
• First order FM screening does not store the ripped file for repeatability.
• Tints are not as smooth as in AM.
• Making moves on press may require new plates (due to less range of movement on press,) which is expensive and time-consuming.
• Small plate imperfections cannot be manually touched up and require a new plate be made.
• Unexpected color shifts can occur in tints of spot colors.

Ink substitution and touch plates
There are ways to work around CMYK being a smaller gamut than RGB. One method is with ink substitution. This keeps a job on a 4-color press, and it works if one color or range of colors is not in the desired gamut. For example, if purple is a dominant color and there are no skin tones or other critical color areas to worry about, rhodamine red or another spot red can be substituted for magenta. Or a fluorescent yellow substituting for process yellow is another example of how you might obtain the results you want. This is not a very scientific process. You need to rely on experienced print professionals whose color sensitivity borders on the paranormal. Many of these people have been in pressrooms and prepress departments for decades and have honed their color sensing skills into a supernatural ability.

Another method of increasing CMYK’s gamut for better color reproduction is Hexachrome printing. Hex is a different prepress workflow that separates and screens the file for the six Hex print colors: Hexachrome Yellow, Hexachrome Orange, Hexachrome Magenta, Hexachrome Cyan, Hexachrome Green, and Hexachrome Black. These are not the regular process colors plus orange and green. These colors are more intense
and designed specifically for high-fidelity color reproduction. Creating a touch plate in your Photoshop file for Hexachrome
Green will not work. The true Hexachrome colors are produced in a Raster Image Processor (RIP) with specialized software for
ripping the six plates necessary at the proper screen angles.

Touch plates are additional plates that are added on additional ink units, requiring a 5 or more color press. Color experts analyze images that are out of gamut and figure out how and where to add a touch plate and also the ink color(s) that will be used. Common touch plate colors are true red, bright green, orange and flourescent colors, colors that are impossible to achieve with CMYK.

Under Color Removal (UCR)
UCR is a method of reducing ink density in areas that have dense, dark colors. Too much ink on the printing sheet can result in a mottling of shadow areas and a loss of detail. UCR is normally done in prepress software. UCR is used to remove density in areas where too much ink would be applied. For example, a “non-standard” rich black of 100% black and 50% each of magenta, yellow, and cyan will result in a screen build of 250%. Adding the percentage of each ink together gives you the total amount of ink you are laying down. A DMAXof 250% is a bit much; 240% is the maximum DMAX (maximum density) recommended for most uncoated paper. (Each printing company sets its own DMAX level depending on its equipment.) In this case, your printer’s prepress department may adjust those percentages by deploying UCR whether those percentages are in an image or in a specified CMYK ink recipe in a program like InDesign.

Gray Component Replacement (GCR)
When there are several inks mixing in the shadow area of an image, sometimes they just muddy up to gray. Substituting a little bit of black ink will create a crisper, deeper, shadow with more detail. In this case, the prepress gurus will identify areas where GCR will help. I do not believe that is standard operating procedure in every print shop, though. For example, don’t expect this service on your brochure for the local Certified Public Accountant with the group picture taken at last year’s holiday party. However, expect it on a coffee table book or a high-end catalog.

Repeatability
Now that run lengths are getting shorter and far more digital repurposing of imagery and branding elements exists, matching printed material from run to run and project to project is critical. You want to be able to print 50,000 brochures for your client and repeat that print run six months later with hardly any visible shift in the color. Second-order FM screening can store job information down to the dot, as can AM screening.

I would love to know how you felt about this topic. Was this too technical? Not technical enough? Do you have any questions about this or would you like me to further explain something?  Do you have a request for a topic for me to cover or elaborate on? I’d love to know, comment or email me at marina @ designingforprint.com

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Managing Image Color and Quality – Part one of two

One of the things designers worry about the most is being disappointed with how a print project turns out. Seeing their project print in the “wrong” colors or not as sharp as it looked on the screen are common issues but there are also others. Many of these issues are surprisingly easy to manage. The good news is that only part of this management is on the designer’s end, some of it is on the printer’s end and out of the designer’s hands. Because printing problems can be expensive, or very expensive to fix (as in redo the entire job ?), there is usually some finger pointing going on when a job goes south. If a designer messes up on their part – they are responsible for paying to reprint the job and I know firsthand, it’s a bitter pill to swallow.

I’ve put together a list of the things you, the designer, controls and those which the printer controls. In this post, I will address the designer’s responsibility. In part two I will address the printer’s responsibility!

Things the designer Controls

Specify the Right Paper
The most important decision you can make is choosing the right paper for your project. No matter what you do on the prepress side to enhance image quality if you are printing a finely detailed image on the wrong paper, the details are going to be lost. Paper choice significantly affects reproduction quality.

Color Manage Your Devices/Workspace
Most designers who are disappointed by color are using a proofing workflow that is not calibrated, ie: their monitor and desktop printer. There’s a reason why the proofing printers that printer’s buy cost five figures (and the color management RIP can cost six figures!), they are way better than your desktop printer. It could be that your printer happened to predict how a job printed in January when you used photo paper and an OEM ink set, trust me, you got lucky. But in June when you are using copy paper with non-OEM ink the whole picture could change (picture, pun, LOL).  Either manage your color at your studio/office or rely on supplied proofs at every step of the process. It’s that simple.

Don’t put off color management thinking you can wait until you see the first set of final proofs from your printer. This can lead to a major color rework during the final hour, delaying the job delivery, and that is not good for you or your client.

  1. There are some really quick and easy ways to calibrate your monitor so you can check color: Google “how to calibrate my monitor,” follow the instructions, and take your monitor’s age into account; as monitors age, they become less accurate.
  2. Get your print provider’s ICC profile, (a standardized data set that describes the color space of an input or output device,)
    and apply it to your monitor and desktop printer. If your desktop printer cannot load an ICC profile, ask your print shop for work-around help or hire an outside firm. Sometimes spending $100 is the best thing you can possibly do.
  3. Take a rhem lighting indicator (RHEM indicator) with you when you show proofs to a client. There’s one in the back
    of the Pantone Color Bridge set. If your proofs look odd or different in your client’s office, it might be the light.
  4. Where are you looking at your proofs? In the parking lot? In the kitchen? In a room with purple walls? Try to check
    proofs in a color-neutral environment; a color booth is best. Specify color while you are in the booth too.
  5. Install 5000k fluorescent lights and daylight incandescents in your workspace.
  6. Do not convert your files to CMYK unless your printer specifically asks you to. Chances are the printer is going to
    want to handle that conversion, especially if your files are printing on a digital press.
  7. If you are printing on colored paper, proof on colored paper. If you can’t proof on colored paper, change the “paper” color in InDesign to approximate your paper color. It will not reflect how transparent inks appear on colored paper, but it’s a step in the right direction.

Rhem indicators show you if your lighting is correct. You can purchase them on a card or a pack of stickers to place on proofs and there is currently one in the back of the Pantone Bridge set. In correct lighting, both halves of the rectangle are identical. Here it is shown in incorrect lighting.

Specify Color Precisely
Using your monitor to select color is a sketchy proposition. You can specify color precisely if you use printed color guides to select your colors. I highly recommend the Pantone Bridge Selector, which gives you Spot, RGB, and CMYK equivalents for each color. When working on identity systems, it is an invaluable tool. You can immediately see how out-of-gamut some Pantone greens and reds are when rendered in CMYK. And for the RGB equivalent enter the values shown in Adobe Photoshop and see how that compares (knowing the browser, monitor and hardware will serve it up differently in each case).

 

Use the Correct Resolution
Resolution is worth mentioning because it causes so many problems in the prepress department. Any image you want to print must be a minimum of 300 dpi at 100% of its actual size. If you pull an image from a website, and it is 4 in. x 4 in. and 72 dpi (the typical web resolution), when you place it in your page layout, it must be sized to 24% of its original size or 0.96 in. x .96 in. in order to be at the correct resolution for printing. (Web designers take note!)

There is absolutely no way to take a low-resolution image and make it look like a high-resolution image. Interpolating a file to a higher resolution makes the image look like an image that was interpolated up to a higher resolution to improve its appearance. One low-resolution image can make collateral look unprofessional. Make sure all the images you provide are the correct resolution for their output size.

The same photo shown in three different light sources, from left: store light, daylight, and home light. Consider the challenges inherent in designing packaging where the product will be viewed in several lighting environments. (Photo courtesy gti Graphictechnology Inc.)

Use Correct File Formats
Each software program creates a native file format that it “gets along with” best. For Adobe Photoshop, that would be bit-mapped files like tiff, jpg, and png. For Adobe Illustrator, it is eps files. Adobe InDesign is a composition program that can accept nearly any file type for inclusion into a document that will be printed or published to the web.

Some file formats work well for print, and some work best for the web. Here are some common file types and their best uses:

Print
• Tiff for high-resolution photographs and scanned graphics
• eps for infinite scalability
• Pdf for high-resolution printing when properly saved with embedded fonts and bleeds, etc.

Web
• Jpg for many compression options and fast loading
• Png for more image depth. The trade-off is its large file size, no CMYK, RGB only.
• Gif limited color (256 only) but very fast loading

Don’t use image compression unless you absolutely have to. Every time an image is compressed (when it is saved) and uncompressed (when it is opened), it rewrites the data in the file and leaves little artifacts/noise in the image. Compression is left over from the days when a 44mb (yes, that’s MB, not GB or TB) Syquest drive cost $200. Nowadays, storage is cheap. Compression works well for the web, but it isn’t necessary for anything else. For example, Tiff files and images are not compressed. Jpeg files and images are.

I hope this helps you to feel super confident the next time you send a job to your printer! Stay tuned for part two – What Your Printer Controls!

Do you have a question about this topic or would you like me to further explain something?  Do you have a request for a topic for me to cover or elaborate on? I’d love to know, comment or email me at marina @ designingforprint.com

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The pudding is in the proof.

Pudding is pretty thick and murky…  the reasons for proofs and types of proofs can seem murky as well. You need proofs, as in you really need proofs. One of the most important things to understand is what type of proof you will need for any given project. We will discuss the different types of proofs and what to look for when proofing print and graphic elements.

How Proofs are Made

A little background on how proofs are made will help you know what types of proofs you need. Proofs are printed on large-format inkjet devices. At the best printers, these devices are calibrated to predict how the job will print. This is an important concept. The proof is not necessarily showing you the most accurate representation of your InDesign file… it is predicting how your file will look when printed on a specific press and paper. Your file whether it is on a Mac or PC is going to be output (interpreted) by a device. That device can be someone’s laptop running a browser if it is a digital project or a printed billboard/package/brochure/card that was printed and therefore interpreted by a RIP. Sometimes, but not always, a proof can be a dot-for-dot proof of your ripped file, but that’s a convo for later.

Because the large-format device is calibrated for the paper it uses, you cannot choose the paper you want for a proof. You have to accept the paper for which the device is calibrated. If you want a proof on the actual paper the job will print on, you will sacrifice color correctness and resolution and it just generally will not work, unless the job is printing digitally.

 

Types of Proofs

Blueline (brown line)   A blueline proof is a low to medium resolution proof in color or black and white. This proof is trimmed, folded, and printed from the final file from which the plates will be made. Blueline and brown-line are terms that belong to a technology that became obsolete in the 1990s, but the terms are still in use. Other equivalent terms are: plotter, folding Epson, folded color digital proof, digital plotter or just plain digital proof.

Contract   A contract proof is the “best” proof for resolution and color. In some, but not all, cases, it is a dot–for–dot proof, which means you will get what you see right down to the halftone dots. This proof is on high-resolution paper. If your project involves multiple pages, ask for your proof in reader’s spreads. Otherwise, you may receive printer’s spreads (which is easier for the printer to do), and it could take a ton of extra time to compare printer’s spreads to an earlier proof in reader’s spreads.

Soft Proof   A soft proof is a proof viewed on a monitor. Not to be used for color. A PDF is a type of soft proof.

Die Strike   A die strike is a sample impression made by a foil or embossing die on the specified paper. This procedure may be done while another job is running, so whatever foil is “on press” may be used. Your printer should supply paper so that the die strike is on the paper on which the job will run. If you also want to see your foil on your paper, specify that so your printer can plan accordingly. That is a press proof and an additional charge.

Press Proof  The actual job on the paper with all finishing techniques applied for a limited quantity.

Drawdown   A drawdown is a proof of specified spot ink on the actual paper that will be used for the job.

One-off  A one-off is a proof of a job that will be digitally printed. Because it is being digitally printed it will be on the press and paper specified. In the case of a large format project, the one-off may be reduced in size or only a critical section may be proofed.

Looking at Proofs

Reviewing a Contract Color Proof

You are going to need a Sharpie®, preferably red, or a similar permanent marker to make your notes and corrections on the proof. Gloss proofing paper is not receptive to many inks, but a Sharpie works very well.

• What are your viewing conditions? Is your lighting color correct? Use the lighting evaluation tool in your Pantone Color Bridge fan deck, if you have one or order a set of Pantone lighting indicator stickers. The photo below shows a RHEM indicator.

This is a RHEM indicator showing that the light in which it is being viewed is not color correct.
When the lighting is correct both halves of the rectangle look the same. 

• Are you at a viewing booth? Should you be? A viewing booth or viewing area is a color-correct environment. If you do not have the proper environment, go to your printer and use his.

Proofing Graphics
• Look closely at every piece of art whether it is a photograph, drawing, or logo.
• Is the color off or correct?
• Is the cropping correct?
• Is the logo the correct version and/or usage?
• Does the image look muddy or fuzzy?
• Does part of the image look dark or muddy?
• Does anything need retouching?
• Was requested retouching performed?
• Are any moirés visible? (this applies only if checking a contract proof that is dot-for-dot)

Proofing Pages
We strongly recommend you proof hard copies. Here is what you want to check on each page:
• Is text flowing correctly from column to column and page to page? Scan the last few words in each column or page, and the beginning of the next column or page to make sure the flow is correct.
• Was the document spell-checked?
• Are headlines complete without missing copy?
• Is the document the correct size?
• Are the margins as specified? Top? Bottom? Outer? Inner? Left? Right? Are the margins consistent?
• Are the folios correct? Does the numbering start on a right-hand page?
• Are there any hyphens or widows that need to be corrected?
• Are columns correct and consistent, justified, or ragged?
• Are elements that bleed cropped correctly?
• Did the binding hide or cut off anything?
• Is the backup, front-to-back orientation, correct? Triple-check this for two-sided postcards, business cards, or any item that changes reader/viewer orientation from front to back, outside to inside. See the two videos below for examples of head-to-foot and head-to-head orientations.

This is what head-to-foot orientation looks like:

This is what head-to-head orientation looks like:

 

Proofing a Paper Dummy
• Is the size correct?
• Is it the right paper(s)?
• Is the color correct?
• Is the weight(s) of the paper correct?
• Is the paper’s finish correct?
• Are the hash marks correct on the proof/dummy?
• Do you have drawdowns? Are they correct?

Proofing a PDF
• If you are reviewing a PDF that was emailed to you or that you downloaded, print it out to size with bleeds and crop marks. Trim it, score it, fold it, and perforate it if necessary. (Having done all this, you will wish you had ordered a hard copy proof from your printer.) If it is a postcard and prints two sides, glue, tape, or staple it together. Is it head-to-head? Head-to-foot? Is the head-to-foot or head-to-head orientation in writing on the purchase order or on the estimate?
• If you receive a hard copy proof, check it for trim, scoring, folding, color, imposition, backup, etc. Note that you should not be checking for spelling at this stage.
•  I do not recommend reviewing pdf proofs on a smartphone. I recently saw a pdf that looked different on two different phones. One showed the error, a key-line around a graphic, and the other did not show it at all. Needless to say, the job printed with the key-line because the client reviewed and okay-ed the proof from his phone.

Proofing Color
• Check the color carefully. Most proofing systems can now proof CMYK color very accurately. If the project is printing with a Pantone spot color, look at a chip or a drawdown and confirm it is the color you want. If the project is printing Hexachrome, HiFi or with touch plates, make sure you are at the press check.
• If you are proofing via an online system, print the proof out yourself so that you will have a hard copy in your hands while you are looking at the job on screen.

PHEW. That seems like a lot of stuff.  If you have a question about proofing or would you like me to further explain something, I’d love to know, comment or email me at marina @ designingforprint.com. Do you have a request for a topic for me to cover or elaborate on? Let me know! Really!

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