User:Tyan.ee/Dragon Tone

Dragon Tone is a new technique/technology used for quality control in the printing industry (especially in offset printing). It is based on using the grey balance as an indicator of printing colour quality. Under standard printing conditions, this allows the press operator to easily tell using the naked eye (under standard lighting) whether the press is printing correctly (i.e. plate alignment, dot gain, ink density, slurring, dot doubling, and overprinting).

History
In printing, a colour bar consisting of all the component colours (typically CMYK) and their halftones is usually printed along an edge of the raw, untrimmed piece of paper along with the reproduction image as a way of checking to see whether the image is printed correctly (e.g. no alignment shifts or change in colour value). The colour bar is then compared with that of the proof for that particular job order or the solid colour patches are measured with a densitometer to verify that colour density is indeed correct. For measuring plate alignment, register marks are printed with the image to show when the plates are misaligned.

Dragon Tone (D-tone) - The Grey Bar
The Dragon Tone grey bar is made up of a continuous line of isosceles triangles where every other triangle is inverted and the sloped sides of each triangle are in contact with the ones adjacent to it. Each triangle is made up of either CMY or K ink (which alternate between triangles) and adjusted to produce a 50% grey. The grey produced from K is maintained at a constant colour shade and is assumed to be constant.

Ink Flow?
When the amount of ink applied to the plate deviates from the balanced level, it is instantly visible on the D-Tone bar. It manifests as a coloured tint in the CMY triangle(s). If the colour is deficient, the CMY triangle(s) will appear to be the tinted opposite colour to that of the deficient one. If the colour is in excess, the CMY triangle(s) will appear to be tinted that colour. Below is a summary of the colour shifts and their interpretation.

Dot Gain
As the 50% halftone is used for D-tone, the grey bar is at its highest sensitivity to dot gain. This means that even the smallest deviations can be detectable by the naked eye, making it extremely easy to use.

Plate Alignment
When the plates are misaligned, it will show up quite clearly on the colour bar as the triangles for that colour will have shifted in the direction of the shift, producing some areas with a deficiency (in the CMY triangle area away from the shift) and some areas with an excess of that colour (in the K triangle or white space towards the shift).

Benefits
There are many possible benefits from using D-tone over the traditional CMYK colour bar.

Environmental
As the grey bar allows any deviations to be easily noticed, it is possible to correct any problems in a timely fashion, resulting in the reduction in the number of rejected prints, saving paper, ink and power. The reduction in wastage can significantly reduce the amount of pollution produced, helping the environment.

Reproducibility
Since the D-tone grey bar specifies that the CMY triangle must be adjusted to produce a balanced grey that matches the shade of the 50%K triangle, as long as the same shade of grey can be reproduced on a reprint job, when used correctly (i.e. when the CMY triangle is balanced), the colour conditions of the first print can be replicated. This allows subsequent editions or reprints of the same book to be printed to the same quality and colour, improving quality consistency.

Multi-press printing
Following from the "Reproducibility" section above, the next logical step is that the same print job (book) can be printed on two or more very different presses and yet still produce a product of consistent quality.

"Proof-less"
With this technology, it is possible that if a proof printed by the customer is printed with a successful D-tone bar, a hard copy needs not be sent by courier to the printer, thus saving on courier costs and time because as long as the printer also prints a D-tone compliant bar for the product (under the same standardized lighting conditions), the product should be the same as the proof.

Transparency of production
With the D-tone bar,