Print by Number :: bvdm MediaStandard Print 2016
感謝學弟提供的 bvdm 新版 MediaStandard Print 2016, 全篇78頁，談的東西很多，我把自己有興趣的部分挑出來整理一下，我主要關心offset printing (Fogra51/52)及其i1可以處理的部分，其他部分就只是整理與參考。
*開宗明義， "Make printing simple"。 標準化就是簡單化，SID 到位加上TVI到位，就這樣而已，真的很簡單。 
*新版本最重要的當然就是這兩組新資料集:
PSO Coated v3 (FOGRA51)
PSO Uncoated v3 (FOGRA52)
*印刷產業的資料集一直都是建立在D50光源之上，AdobeRGB(1998) 及 sRGB(1999)則是在D65，bvdm 鍵議要轉到同為D50 的 eciRGB_v2(2008)上，這點我也很期待，但實要際運作我覺得有點困難。
eciRGB_v2(2008)除了白點在D50外，其色域涵蓋範圍比較完整；相對的，AdobeRGB 在青色(Cyan)有一點不足，sRGB則是根本不夠。
*印刷相關描述條件:
印刷方式(e.g.Offset)
紙張條件: (e.g. premium-coated white)，基重(e.g. 80 g/m² to 250 g/m²)，光澤及白度( e.g. matt, moderate)
網數: (e.g. 60/cm to 80/cm)， FM 點最小直徑 (e.g. 20 μm)。
特性曲線(e.g. A)
主色(CMYK)及二次色(RGB) L*a*b*定義值。
*"ISO Newspaper 26” 將由 "WAN-IFRAnewspaper26v5" 取代。
*heatset web offset 延用舊規格。
*coldset printing condition 在 ProcessStandard Offset 裏代號為 C8。
*Publication gravure: printing conditions in accordance with ECI ProcessStandard Gravure 2009 依然有效。
*Packaging gravure 及 flexo 尚未被標準化。
*n-channel inkjet printing system 建議使用RGB 流程。
*車間軟打樣(softproof-to-press, pressroom proof) 需要以下幾個要件:
. 一個以上的廣色域平面顯示器，備有遮光設施，能被硬體調控及校正。
. 具備控制方法。
. 顯示器的 icc profile。
. 可調節的光源。
. 光譜儀。
*數位打樣相關規範:色差計算由CIELAB(1976)改為CIEDE2000，因計算方法不同而有數值呈現不同，實質內容差異不大。
* CIELAB(1976)與CIEDE2000色差概念的差異，這個圖好用，標記一下。
**按bvdm流程，來源RGB資料須先轉到eciRGBv2 RGB 再分色到 PSO Coated v3 CMYK。
eciRGB慨念很好(D50 & Gamut)，但多一道程序，台灣產業在想法及作法上不曉得甚麼時候才能跟上來，AdobeRGB 繼續撐著用。
* 
*The diameter of the smallest screen element in non-periodic screens (FM and hybrid screens) should be in the region
of 20 μm (coated papers) and 30 μm (uncoated papers).
標記一下:FM網點直徑在塗佈紙為20μm，非塗佈紙為30μm
*— Printing tone value range
• Sheet-fed offset, heatset and narrow web offset: 2 % to 98 %, safe 3 % to 97 %, on uncoated paper 4 % to 96 %
塗佈紙網點呈現須2%-98%，非塗佈紙為4%-96%。
• Coldset web offset printing (newspaper printing): 3 % to c. 90 %, even larger in waterless coldset
• Gravure: 3 % to 95 %
• Flexo: depending on substrate (film, paper, corrugated) and use of a hybrid screen spreading in highlights and shadows.
*— Maximum tone value sum
• Sheet-fed offset: ≤ 330 %, usually 300 %
總墨量≤ 330 %, 通常在 300 %
• Heatset web offset: coated papers ≤ 300 %, uncoated papers ≤ 270 %
• Coldset web offset: ≤ 240 %, in the v5 standard profile 220 %
• Gravure: ≤ 360 % (ProcessStandard Gravure), frequently ≤ 340 %
*Boxes in PDF documents : 做PDF程式常會遇到這些參數，標記一下。 
*Colour composition settings : 灰/黑分色設定，標記一下。 
*— Black solids
In multi-colour printing black solids can be underlain with c. 50 % cyan.
*Non-contract grey balance values in accordance with ISO 12647-2:2013 that typically serve as a guide if no standard ICC profile is applied
這個有意思；沒特定色彩目標(如Fogra39, JapanColor…)的話，走灰平衡就好了。不過這裡只有目標值，不曉得寬容怎麼算，以G7來講是df< 3。
*軟打樣相關規範: 主要是 ISO 12646(2015)與 ISO 3664(2009)，其中提到如視角色差(需用到 tele-spectroradiometry )就不是i1可以處理的，建議到Fogra網站去查詢符合規格的顯示器會比較快。
#ISO 12646:2015–Properties of colour proofing monitors
B等級設備: 單一色塊視角度色差(angle dependent colour differences)小於10, (ΔE00 < 10)
A等級設備: angle dependent gradation stability ΔY(TRC) < 10 %
均勻性(Homogeneity): Stability of colour rendering (ΔE00 < 4) and gradation over the surface (normative), pixel error class 0 in accordance with ISO 9241-307 (informative)
Monitor measurements: Use of spectral measurement devices, inclusion of the surroundings (tele-spectroradiometry)
#ISO 3664:2009 – Viewing conditions (booths and viewing stations in softproofing applications)
這裡是我以前較少注意到的，標記一下:看色光源訂在2000lx左右，算蠻亮的，這裡指的應該是車間控墨台前的軟打樣，印前環境應該沒這麼亮，還有就是2000lx下，顯示器亮度放在120 cd/m²一定太暗，我這方面的操作有必要修正一下。
Conformity classes P1 (high) and P2 (low):
General and special colour rendering index, metamerism index, UV component confirms physically to D50, homogeneity of the illumination, neutral surroundings, servicing devices
Range of illuminance maximum: 2000 lx ± 500 lx, minimum 500 lx ± 125 lx (when dimming the colour temperature should remain as similar as possible, i.e. white point does not shift)
* — Appraisal (accordance with ISO 3664:2009:)
• D50 (5000 kelvin) standard illuminant with physically correct UV component
• Illuminance; 2000 lx ± 500 lx
• Glare-free angle between illumination (angle of incidence 0°) and observation (viewing angle 45°)
*— Adjusting the illuminance of the viewing light to the monitor luminance
A luminance limit of 160 cd/m² was imposed before the revision of the standard in 2015 due to the ageing of CRT and LCD monitors but it no longer applies today. As a result, the illuminance no longer needs to be dimmed to 500 lx ± 125 lx.What is, however, crucial is a match between the individual choice of monitor luminance, eg. 200 or 300 cd/m², and a corresponding reduction in the maximum illuminance of 2000 lx that reflects industry practice.
這裡提到新的顯示技術不必被限制在160 cd/m²以下，所以，看色光源不必降到500 lx；在2000lx光源下，顯示器亮度可在200 or 300 cd/m²不再是之前的 120c d/m²。
*— Viewing conditions (visual colour appraisal)
Matching procedures and other critical appraisals require a high illuminance of 2000 lx ± 500 lx, because it is only then that minor differences become apparent. A standard D50 (5000 K) illuminant must be used. The specimens must be placed on a matt white backing and surrounded by a matt grey surface with a colour density of 0.7 (in relation to ideal white)
*Suggested resolution values (pixels per inch) for the delivery of unscreened data. These pixel values should not
be exceeded by more than a half 
*Solid colouring aim values and tolerances for press proofs and production prints
SID 色彩值定義，Fogra51 (new) & Fogra39(old):
*SID 在 Proof， Production 及 Fluctuation 的寬容值。 
*Aim values for production run solid colouring in illustration gravure
凹版參考
*Solid colouring aim values (rounded CIELAB colour values for the solid vertex colours) in screen printing
網印參考 
*Tone value increases in accordance with ISO 12647-2
Fogra51 走 A曲線。
*— Colour measurement conditions
The bvdm has reservations about the use of the new CIEDE2000 colour difference formula. Not only are the values calculated using CIELAB(1976) and CIEDE2000 not compatible, its application only makes sense for proof printing (ISO 126417-7:2016), because in this process a reverse control of the colour channels needs to be carried out from time to time. Whereas, during production printing (parts 2 to 6 of the standard), it is a matter of stabilizing the printing process, and where, in the best case, individual primary colours need to be balanced. CIELAB(1976) is tried and tested for this and is outstandingly suitable, whereas CIEDE2000 is not. Consequently, at least for parts 2 to 5 of the standard, the bvdm advises againt the CIEDE2000 formula, which is in any case only informative.
bvdm 認為在生產中的控制，穩定性是更重要的，CIELAB(1976)經過長期運作證明是可靠的，所以bvdm認為在印機控制時還是用CIELAB(1976)而不是CIEDE2000 。我在Beer’s Law的運用上，CIEDE2000相對較鬆散，CIELAB(1976)會比較好操作。
*— Density measurement conditions
Under the ISO 5 series of standards, CMYK primary colours should be measured densitometrically with a filter in accordance with ‘Status E’ (ISO 5-3). This means that compared with the US guidelines (‘Status T’) a narrow band evaluation takes place for colour channel Y. As a result the solid Y colour density is nearly as high as those for C and M. Spot colours are measured with the colour channel that yields the highest colour density. Measurements should normally be made with polarization filters. One exception is the measurement of offset plates (if no plate measurement device is available) and possibly the characterization of a proofer. The following also apply: matt white backing for the specimen (unlike ISO 13655), matt black specimen backing for production run process control. When using spectrophotometers with densitomtric functions (spectraldensitometer) measurement mode M3 should be selected
bvdm 認為 Status E 相對於 Status T 在Y的濃度會更相近於CM，所以提議用 Status E 濃度，我覺得無妨，在管理上只要維持一致性即可。SPOT color 用Sopt filter 方式會比bvdm提到的"取最高值”(with the colour channel that yields the highest colour density)要好。
*Course of a permanence test for digital proof prints
數位樣乾燥時間規範參考。 
以上，有不同看法或補充都歡迎提出。
Tags: bvdm. mediaStandard Print 2016, Color management system, eiRGB, 軟打樣, Fogra 39, Fogra 51, ISO 12647-2, ISO 3664, soft proof, 印刷標準化
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