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Inkjet Printing

Inkjet Printing. by Brian Smith LRPS. Print Quality Factors. Colour Rendition Colour Casts Neutral Greys Saturation Smooth tones Brightness & Contrast Sharpness Other Faults. Test Evaluation - colour. Rich Blues Gradients Skin colour and smoothness Shadow separation

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Inkjet Printing

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  1. Inkjet Printing byBrian Smith LRPS

  2. Print Quality Factors • Colour Rendition • Colour Casts • Neutral Greys • Saturation • Smooth tones • Brightness & Contrast • Sharpness • Other Faults

  3. Test Evaluation - colour • Rich Blues • Gradients • Skin colour and smoothness • Shadow separation • Sky Blue, and highlight detail • Natural hues • Bright Reds • Neutral monochrome • Sharpness • Texture in all colours

  4. Test Evaluation - mono • Maximum blackSmooth gradientNeutral mid-greyHighlight contrast & detailShadow separationFull tonal rangevisible and neutral

  5. Print Rendition • Causes of poor prints • Poor image • Printer faults • Wrong or incompatible paper & ink • Software

  6. Printer Faults • Misaligned heads • Clogged nozzles • Depleted cartridge(s) • Mechanical malfunctions • Pizza wheel marks • Scratches (paper thickness?) • Paper curl • Ink deposits from rollers

  7. Papers & Inks • Paper type • Matte • Glossy & Lustre/Pearl • Swellable vs Micro-Porous • Cotton Rag • Baryta (Fibre) • Inks • Dye • Pigment • OEM vs Compatible

  8. The need for coated paper Uncoated media Uncontrolled ink spread Bleed & strike-through due to porous substrate Lower density due to absorption Poor fade resistance Cockle Coated media Controlled ink spread High resolution Large colour gamut Stays flat Better fade resistance Inkjet coating PE coating Base Paper

  9. Dyes, Pigments & Gloss Pigments stay (mainly) on the surface & cause diffuse reflection Dyes are absorbed by the coating, direct reflection, glossy appearance is maintained

  10. Inkjet Inks Generalities Dye based inks Bright colours Quicker fading Sensitive to oxidizing Glossy media available Colours vary more with different papers Low water resistance after printed Pigmented inks Less bright colours Fade resistant Wide range of Matte surfaces Fewer glossy options available Good weather resistance

  11. Paper vs Ink problems • Colour! • Wrong profile or driver setting? • Poor contrast (D-Max) • Banding • Metamarism • Blotching (slow drying) • Gloss differential • Bronzing

  12. Why is monochrome so difficult? Because making grey by mixing C+M+Y is extremely difficult

  13. Printer Ink Sets C+M+Y+K – normal printing & consumer inkjets C+M+Y+K+Lm+Lc - Photo inkjets C+M+Y+PK+MK+Lm+Lc+Lk - HP Vivera C+M+Y+K+Lm+Lc+Lk+Llk - Epson K3 Ultrachrome C+M+Y+K+Lm+Lc+Lk+Llk+Red+Blue – Canon ChromaLife More inks deliver wider gamut

  14. Ink Starts Two blacks Three blacks

  15. What’s the solution? Use the printer’s default monochrome settings Use monochrome (low chroma) inks Use special (extended grey) ICC colour profiles Use “grey balancing” software Use a RIP (raster image processor) Use a printer that has 2 or 3 black inks

  16. Printing Software Photo Editor Application Printer Driver PC/Operating System

  17. Colour Management • Non-managed printing • Assumes sRGB files • Colours controlled by driver • Colour Managed • By driver OR printing software • Double profiling typically gives a magenta cast • Built-in profiles for manufacturers papers only • Custom profiles are more accurate Demo: Print Drivers

  18. Resolution • dpi – dots per inch (e.g. 2400: Canon, HP, 2880: Epson) - internal to printer • ppi – pixels per inch (e.g. 300, 360) – determines how large your print will be. • 300 ppi is an industry standard for commercial printing (e.g. magazines) • 240 ppi is easily sufficient for high quality inkjet printing

  19. Print Size Consider a 6MB image: 3000 x 2000 pixels • At 300 ppi -> 10” x 6.6” print • At 200 ppi -> 15” x 10” print • If you actually want a 12” x 8” print, then print at 250 ppi. • In all cases, the image itself is unchanged.

  20. What actually happens Photoshop/Elements • Print 6MB photo at 250 ppi • Resampled to internal resolution (600 ppi) • Data (35MB) transmitted via USB connection • Outputs ink droplets at 2400 dpi Printer Driver PC/Operating System

  21. Resampling (upsizing) • Printers have a native resolution: • Epson = 720 ppi • Canon & HP = 600 ppi • Printing at exact multiples can give higher quality • 180 or 360 for Epson • 150 or 300 for HP, Canon • Resample: Photoshop, Genuine Fractals etc. • Use Qimage

  22. Qimage Qimage Qimage Qimage Qimage Qimage Qimage Qimage Qimage Qimage • Print 6MB photo as 12x8 • Resampled to printer driver resolution (600 ppi) • Apply sharpening etc. • Pass through (35MB) image data • Data transmitted via USB connection • Outputs ink droplets at 2400 dpi Printer Driver PC/Operating System

  23. Sharpening • Images to be printed MUST be sharpened a little to compensate for ink diffusion • Over-sharpening is easily achieved, and harshly judged Demo: Examples

  24. Summary Tips • If you find colour management complex, stick to an unmanaged workflow: • Use sRGB colour space • Use manufacturers papers and inks • Find the right driver settings, and stick with them • Managed workflow offers more options, but more pitfalls • Limit the range of papers you use, and learn their characteristics • Have custom profiles made for non-OEM papers • Don’t keep changing your workflow – consistency in results comes from consistency in approach • Do a nozzle check before an important print run • Print a test image periodically…

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