Goodbye JPEG - hello WEBP?

Google is introducing a new open-source image format: "WebP" (pronounced ‘weppy’).

Google claims that images in the WebP image format will be close to 40 percent smaller than JPEG files while providing for images that are of higher quality by virtually eliminating the image artifacts associated with JPEG compression. At the present moment, WebP is still in a very early stage of development and hence, unlike the JPEG file format, WebP is not yet built into cameras, web browsers, image-editing programs, etc.

JPEG vs WebP compression at 100%From left to right: Original image, JPEG compressed, WebP compressed.JPEG vs WebP compression enlargedFrom left to right: Original image, JPEG compressed, WebP compressed.
WebP uses the Y'UV color model that is used in the NTSC, PAL, and SECAM composite color video standards. It is a bit like the LAB mode color model that is used in PhotoShop, and other imaging applications, in that the Y component, like the "L" channel, determines the lightness of the color (referred to as luminance or luma), while the U and V components, like the "a" and "b" channels, determine the color itself (the chroma).The Y'UV color model - From left to right: Original composite image, "Y" component, "U" component, "V" component.
For image compression, WebP uses the VP8 video codec - the same methodology that is used to compress keyframes in videos. This codec uses predictive coding to encode an image by using the values in neighboring blocks of pixels to predict the values in a block, and then encodes only the difference (residual) between the actual values and the prediction. The residuals typically contain many zero values, which can be compressed much more effectively.

So far, while it is still a "lossy" compression technology, WebP compressed images certainly appear to deliver a higher level of compression (and thus smaller file size), and much higher image quality than the current standard JPEG image compression method. This is a good thing, not only for images for web application, but possibly for print application as well.

Google Chrome will likely be the first consumer application to support "weppy" compression in order to provide a faster user experience on web sites while reducing bandwidth and hosting costs.

On the other hand

Since the Y'UV color model is similar in principal to the Lab color model...why not apply the same compression methodology to an image that's in Lab mode? I've done some testing with high JPEG compression of the "a" and "b" channels of a Lab image and easily achieve file sizes that are only 20% of the original file size with no apparent image degradation. In fact they look very similar to the results obtained with the WebP image format.
Left image WebP - right image Lab compressed using very high JPEG compression for the "a" and "b" channels of an Lab image.
Left image WebP - right image Lab compressed using very high JPEG compression for the "a" and "b" channels of an Lab image.
If the Y'UV compression method could be applied to Lab images then the graphic arts industry could continue to use a color model that is well understood and in use today rather than import a new color model from another industry.

Eliminating show-through in scans and/or photocopies

Paper is a fairly translucent substrate. The thinner/lighter weight or higher quality the paper the more translucent it is. The result is "show-through" - seeing a ghost image of what was printed on the reverse side - whether reading the page itself or scanning/photocopying it.
Scan with color bar and text on the next page showing-through.Close up view of show-through.
To eliminate show-through in scans and/or photocopies, simply place a piece of black paper behind the sheet that you are scanning. This evens out the tonality of the page and effectively eliminates show-through.

The right loupe for the job

Spend any time in a printshop and you'll quickly discover that press operators, and even print buyers, depend on their loupes to help inform them about the quality of plates, proofs, and presswork.This is a quick guide to help you choose the correct instrument for your needs. Beside each type of loupe/microscope is an image to approximate the view through that instrument. Keep in mind that all loupes and microscopes have limitations based on the laws of optics and that prices can vary widely. That is why having more than one instrument is usually best. In general the higher the magnification the smaller the field of view, the shallower the depth of view, and the closer the instrument must be to the subject. A single lens is satisfactory for low power loupes but higher power ones require two or more lens elements for improved resolution and correction of chromatic aberrations, distortion, and improved flatness of field (i.e. the entire viewed area appears in focus rather than just a small area in the center of the view).

Wide field comparator - 2x-6x ~ $50-$100As its name implies, comparator loupes are typically used to compare two items, e.g. proof to press sheet, different paper surfaces, halftone screening methods, proof reading, etc.
Pros: Long eye relief coupled with a wide, flat field of view allows it to be shared by more than one viewer at a time without moving the loupe. Cut-away base allows room for touch-ups or mechanical changes to the item under inspection. Can be used to evaluate large scale issues such as halftone rosette structures and paper/ink mottle.
Cons: Rather limited applications in prepress/press relative to the cost. Low magnification does not reveal halftone quality issues.

Linen tester/folding loupe - 2x-10x ~ $25This is the iconic press operator's loupe.
Use: Good for checking registration and macro imaging problems like rosette structure integrity and mottle.
Pros: Inexpensive, portable, easily available.
Cons: Low magnification does not reveal halftone quality issues. No focus adjustment.

Folding loupe (a.k.a. Hastings loupe, Hastings Triplet, Swing Loupe) - 10x-25x ~ $70This is arguably the type of loupe actually most used by press operators. Highly recommended as a good all 'round basic loupe.
Use: Good for checking registration and macro imaging problems like rosette structure integrity and mottle. Higher magnification begins to identify issues such as slur and doubling.
Pros: Relatively inexpensive, portable.
Cons: None.

Rigid loupe - 10x-75x ~ $650This magnifier is sometimes used in the press room but is more often used by a Quality Assurance Manager. Very flexible in that it can be customized with different lens options.
Use: Good for checking registration and with higher magnification, to identify issues such as slur and doubling.
Pros: Optional lenses can customize unit for specific shop needs. May come with color filters to enhance the visibility of dot structures. Built-in light.
Cons: Very expensive.

Pen microscope - 25x-100x ~ $100This magnifier can be used in the press room and prepress. 50X is most popular - 75-100x is very good for checking FM screening. An excellent all 'round high magnification tool.
Use: Very good for identifying imaging issues such as slur and doubling.
Pros: Convenient pocket size. Can be focused by manually tilting it but can be difficult to hold steady.
Cons: Expensive.

Lab-type microscope - 25x-100x ~ $250This magnifier tends to be more often used by a Quality Assurance Manager in a lab setting. 75-100x is most popular and very good for checking FM screening.
Use: Very good for identifying imaging issues such as slur and doubling.
Pros: Built-in measuring reticle scale is helpful in analyzing halftone structures.
Cons: Expensive. Typically produces an inverted view.

Digital video microscope - 20x-200x ~ $125This magnifier tends to be more often used by a Quality Assurance Manager in a lab setting. 200x is most popular and is ideal for checking FM screening as well as detailed analysis of halftone issues. A must-have for any print/prepress shop.
Use: Excellent for identifying imaging issues such as slur and doubling and analyzing halftone reproduction issues. Ability to take photos and videos of halftones and other micro-features enables better record keeping as well as remote diagnostics. Build-in light helps with image quality. Software may be included for more detailed image analysis.
Pros: Still and video image capture. High magnification. Ability to process images with image analysis software. Ability to document and share image capture. Relatively inexpensive.
Cons: Must be tethered to a computer.

Where to buy
Shops that sell binoculars/telescopes, collectibles/stamps, and hobbyist supplies will also carry a selection of loupes and microscopes.
If your local shops can not source what you need - online sources include: http://www.edmundoptics.com, http://www.betascreen.com, http://www.amazon.com, http://www.ebay.com/


Addendum
A reader, "Otherthoughts" described some of his experiences with the lab-type and pen microscopes.

"Regarding inversion and some background about why this was/is important to me.

I used a 25x scope like this for inspecting things a little closer during my press-man/press-room days.Mine had a metric measuring reticle in it. Sometimes I would break this scope out and measure how far off the register marks were and then I would input the distance corrections into the press control unit. On the next pull, the marks would be almost perfectly registered. I only did this when the register marks were way off and/or I wanted to impress someone. The main reason I didn't use the scope more often as a Pressman, was because of it's inverted view. It's a pain to keep mumbling to yourself "left is right and up is down" when using this type of scope.

Without exception, every single stand/pen microscope that I've ever looked through at a trade show or that a vendor has shown to me in the press-room, has produced an inverted view as well. I always wanted to buy a right reading stand microscope of 25x or more, but I've never found one.

I know things have changed quite a bit since my days in the field. Nonetheless, there will still be directional components to the things that will be evaluated using these microscopes, e.g. slur, doubling, etc. and you will likely still have to remind yourself that "left is right and up is down" while evaluating their cause, meaning and remedies."

Thanks for the contribution Otherthoughts!

Every letter tells a story - print problems revealed in type reproduction.

Spend even a small amount of time in a printshop and you'll quickly realize how much effort press operators put into scrutinizing their presswork through a loupe. The two things they're typically looking for are clear centered rosettes - this tells them that the presswork is in register – and print problems revealed by how well individual letters of type are reproduced in print.

Here's how type printed offset reveals problems:

Normal ink transfer - no apparent problems.


Doubling
A ghost image appears just behind the primary graphic causing an increase in dot gain. More information about doubling HERE

Slur
A smeared ghost image appears just behind the primary graphic. More information about slur HERE

Over emulsified (a.k.a. emulsified, water logged)
Ink is designed to accept a small amount of water (fountain solution) on press. Too much water appears as tiny droplets in solid areas and reduces gamut, image sharpness, contrast, and increases dot gain.

Tailing (a.k.a. misting, slinging)
Too high a solid ink density or ink that's too "long" can cause thin "tails" of ink strands to appear extending behind the primary image causing a loss of sharpness, contrast and an increase in dot gain.

Picking (a.k.a. pinholing)
Small white specks appear in solids. This usually results because the ink tack is too high or there is not enough impression cylinder pressure ("squeeze").

Ink breakdown
On press, fountain solution acts like a solvent. If it is too aggressive or acidic it can break down the ink that forms the image resulting in presswork that appears muddy and/or "soft." It also reduces total gamut because it reduces overprint trapping efficiency.

How was it printed? Simple ways to determine the printing method used.

The proliferation of new printing technologies like commercial production toner and ink jet presses as well as the rapid increase in quality of some traditional systems like flexography, has made it a bit difficult to determine exactly which printing method was used for a given sample. Was it offset or digital ink jet? Flexo or offset?

Here is a guide to help you identify which printing method has been used. The best method is to look very closely with a loupe at the letter forms and then confirm by looking at the halftone dots themselves. Although these images were taken at about 200x to show as much detail as possible, they are not that different than what would be seen by the human eye under a loupe at 10-20x.

Offset lithography

Type edges are sharp and well defined. The ink density is similar across the letter. The paper around the printed ink is usually clear/unprinted. The sharpness and consistent ink density is reflected in the halftone dots. Note that this same sharp appearance occurs if the halftone screen used is FM (the third image) rather than AM (second image).
Gravure

All graphic elements appear halftone screened so the edges of text show a rough halftone appearance. Although presswork color may appear rich, viewed under a loupe, the halftone dots may have a watery appearance. Individual dots may appear to have a hole in their centers.
Flexography

Flexography uses a rubber-like plate that, under pressure, transfers ink to the substrate. This results in type that often appear to be surrounded by a sharp-edged "halo." The same effect, but in opposite, occurs in the halftone dots which may have dark edges and light centers. Both type and halftone dots usually have very sharp and well defined edges. Note that this dot sharpness also occurs with an FM screen printed with flexo (third image).
Electrophotographic (a.k.a. laser toner, Xerographic)

With electrophotographic systems the image is created by depositing a powder toner. This results in a "sprayed on" appearance. Type edges are soft and there are often specks of wayward toner on what should be unprinted paper. On close examination you'll likely see apparently random Yellow dots. Those are anti-counterfeiting tags. Halftone dots have a similar fuzzy appearance.
Inkjet

Under a loupe, ink jet type has a "blocky" "chunky" edge appearance. This is caused by the low resolution/large droplet size typical of these devices (despite the claims of high dpi). Sometimes there will be the occasional "satellite" ink droplet near the letter (two are shown in the image below). Because of the way the ink is sprayed onto the substrate, halftoned areas appear to be done with an FM screen. However, unlike the FM screening used in offset lithography, there is usually no apparent pattern or organization to the dots.
Engraving

Engraving is typically used for currency/bank note printing, stamps, and sometimes very exclusive stationary. Type is very crisp and sharp. The process is capable of extremely fine detail and as a result is used to print security microtype. Halftones are usually created with line effects rather than a conventional halftone screen. Softly passing one's fingers over the printed work will reveal a tangible texture due to the raised ink.
Thermography

Thermography is commonly used on wedding invitations, letterheads, business cards, and greetings cards as an attractive alternative to the more expensive engraving process. Type has a raised surface texture similar to engraving however, with thermography type appears to be printed under a transparent coating. The low resolution of this process makes it unsuitable for quality halftone screening.
LCD display (print to screen - just for fun)

The letter "e" as displayed black against a white background on my laptop's display. Since the LCD display produces no light of its own, it requires a cold cathode fluorescent lamp situated behind the LCD panel. Electronically-modulated pixels filled with liquid crystals are arrayed in front of the light source to produce images in color. Passing the backlight through the red, green, and blue liquid crystals recreates the backlight white, while blocking the backlight creates black. Anti-aliasing of the letter helps to smooth the shape of the letter form and compensates for the relatively low resolution of the screen itself. Note that the pixels forming the image are not square but rectangles.

Optimizing images in 8 easy steps - the real basic basics

Who this post is for
Designers and people who supply images to printers and want to provide the best image possible without a lot of technical complication. Also, printers who receive poor quality images who want to help their customers tweak images to get a better result.

The software
I'm using PhotoShop CS3, but any image editing software that is capable of doing these basic manipulations will work.

The image
I'll be using this image:because it has, I hope you can see, some obvious color problems. The image is from the daughter of make-up man Harry Buchman who worked on the movie "Jaws."

The 8 basic steps
There are many ways and tools that achieve the same or similar results - most are very simple, but like anything they can be made more complicated. This following is a basic, pragmatic, method to getting better images for reproduction.

These are the 8 steps:
1) Check the computer monitor display to make sure that it is representing the tone scale correctly.
2) Check the computer monitor display to make sure that it is representing neutrals correctly.
3) Check the image resolution.
4) Set the color target.
5) Adjust color
- with an "auto-correction".
- with a manual correction.
6) Set Black and white points.
7) Adjust contrast.
8) Sharpen image and save (under a new name).

Step One - the tone scale
Download this graphic and open it in your image editing application:You should see a 21 step ramp going from 0% on the left to 100% black on the right. The black should look black and the white look white. You should be able to distinguish every patch of grey separate from each other however it is acceptable if the last two patches (95% and 100%) blend together.

Step Two - neutrality
The patches of grey in the graphic should all look neutral.

If your display passes #1 and #2 then you're good to go. If not, you may need more sophisticated help.

Step Three - image resolution
Check the image resolution. Typically the image size is based on a resolution of 72 pixels per inch (a.k.a. 72 dpi):This image is sized at 8.333" x 5.625" at 72 pixels per inch. 72 pixels per inch is pretty standard for web pages. For printing, a higher resolution is required. Changing the resolution of this image to 300 pixels per inch with "resample" not selected: shows that this image is only suitable to be reproduced in print at a size of 2" x 1.35". An image resolution of 300 pixels per inch (a.k.a. 300 dpi) at 100% reproduction size is quite standard for print application.

Step Four - set the color target
This tells the image editing application what the intent, or final destination, of the image is and helps it to display the image correctly. The color target is embodied in a color profile.
The two most common color profiles used are:
1) sRGB - which is used for images destined for the web or printed on desktop inkjet and photofinishing printers.
2) Adobe 1998 - which is used for images destined for print reproduction.By default, most digital cameras embed the sRGB profile. It can be reassigned to the Adobe 1998 profile if the destination is a printing press.

Step Five - adjust color
Auto-correction
Many image editing applications have an auto-correction capability:Sometimes that will give an acceptable result or one that can be a base for further work:Auto-correction tends to work best with images that contain a great variety of colors.

OR

Manual-correction
Manual color correction takes four steps:
1) identify neutrals
2) neutralize mid-tones
3) neutralize shadow-tones
4) neutralize highlight-tones

This image contains several likely neutrals:The highlights on the water, the midtones of the beret, the shadow-tones in the darkest part of the vest.

Use the eyedropper tool to measure the RGB values of the mid tones in the beret:The eyedropper indicates that the RGB values in this part of the image is:
R 131
G 71
B 60

The large number for RGB relative to the G and B values indicates that the image has a red cast (too much red). To be neutral grey the RGB values should be similar. By adjusting the RGB color values so that they are similar makes the mid-tones represented by this area of the image neutral:It's not important that the RGB values are absolutely identical - close enough is good enough.
In this case the final RGB values are:
R 81
G 87
B 85
Note that the color adjustment is balanced in that Red is lowered while Green and Blue are increased.

Repeat the color adjustment, using the same procedure for the highlights and the shadows.

The result:
Step Six - adjust black and white points
Use the "eye dropper" tool in concert with the "Show Info" dialog box to get the RGB values of the specular highlights. Highlights that should be absolutely white with no detail:Pure, no detail white should have RGB values of 255 each. This image's values are:
R 242
G 235
B 235
Which means that although they may appear white - the highlights are actually grey. Adjusting the highlights using the "level adjustment" option sets the highlights to their appropriate values:The same thing would then be done to the darkest black in the image which should be close to:
R 0
G 0
B 0

The result:
Step Seven - adjust contrast
Adjusting contrast changes the relationship of the tones of the image making it appear "harsher" or "softer. The "Curves" menu option is used to alter contrast:
Step Eight - sharpen image and save (under a new name)
The final steps are to "sharpen" the image (of which there are many different methods):In general, images destined for the web should be sharpened enough so that they look "natural". Images destined for print should appear slightly over-sharpened, a bit harsh looking because halftoning has a bit of a softening effect on images.

So, following these "simple" 8 steps, here's where we started:And here's where we ended:
Obviously more work could be done on the image. Other, more sophisticated, methods could be used. However following these simple 8 steps should provide much better results for those people who don't want to get too technically involved.