The printed proof is a dispassionate simulation of the ultimate output – a CMYK press sheet. The mission of a proofing system is to create accurate predictions, not pretty pictures. The primary goal of ‘proofing’ is to serve as a tool for customer verification that the entire job is accurate. Prepress proofing (also known as off-press proofing) is a cost-effective way of providing a visual copy without the expense of creating a Press Proof. If errors are found during the printing process on press, correcting them can prove very costly to one or both parties involved. A Contract Proof usually serves as an agreement between customer and printer and as a color reference guide for adjusting the press before the final press run. Most contract proofs are a Prepress Proof.
Digital Proofs and Press Proofs
There are mainly 2 types of proofs, the digital proofs and the press proofs.
The press proofs, also called wet proofs is the most accurate and costly proofs both for four color and pantone color jobs. Wet proofs use the exact paper and inks to be used in the final job and therefore give an exact representation of the finished job. It requires special set-up on press and special plate output which makes it a pricier proofing option. However, this type of proofing process yields the best color proofing result. Wet-Proof is an option especially recommended on projects that are critical on colors. This includes art books; museum quality projects and photography books.
The digital proof, sometimes also called color proof, provides the color-reliable/color-true reproduction of the contents of the file intended for printing. Color proof is made with inkjet printers or thermal sublimation printers in combination with powerful color-management systems. Proofing is usually performed in full-size format, but in some cases small-page format is also acceptable. Color proof serves as a guideline for a printing press operator, and usually stands for a contract proof.
Below is the comparison of the digital proofs and the wet proofs.
Digital Proofs vs. Wet Proofs:
Advantages of Digital Proofs
The cost to output digital proofs is more competitive compared with wet proofs if only one set of proofs is required.
Preparing digital proofs are faster than preparing wet proofs.
There are fewer problems with dirt, spots, or registration problems which are common in wet proofing.
Translating Digital proofs to Printed sheets: digital proofs are warmer than wet proofs because of the nature of chemical ink–it is different from actual printing ink. The color tolerance between digital proofs against the press sheet is about 10% to 15%.
Digital proofs are the fastest to output (it takes about thirty minutes to output eight pages of an A4 size).
Disadvantages of Digital Proofs
Digital proofs do not reveal problems in the files, such as trapping, overprints, or moirés.
The tint colors in digital proofs cannot be matched during actual printing.
PMS colors are not accurate in digital proofing as it is in wet proofing.
Digital proofs are not suitable for black and white images, duotone, or 4-color black and white images.
Lineart or rules will be thicker than actual size due to distortion.
Digital proofs are printed on digital paper so the color will be slightly different because is not on the “actual” paper.
Advantages of Wet proofs from CTP Plates
The cost to output wet proofs is more economical if several sets of proofs are needed.
The color is more accurate for black and white, duotone, and 4-color black and white images or for PMS colors.
Problems in the files will be apparent, such as trapping, overprints, and or moirés.
Wet proofs use the same paper type and weight as it will be used during manufacturing.
Disadvantages of Wet proofs from CTP Plates
Wet proofs take longer to prepare than digital proofs.
Dirt, spots, and registration problems cannot be avoided.
The cost of outputting wet proofs is high if only one or two sets of proofs are needed.