1. Inkjet Printing
by Brian Smith LRPS

2. Print Quality Factors Colour Rendition Brightness & Contrast Sharpness
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 black Smooth gradient Neutral mid-grey Highlight contrast & detail Shadow separation Full tonal range visible 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 Inks Matte Glossy & Lustre/Pearl
Swellable vs Micro-Porous
Cotton Rag
Baryta (Fibre)
Inks
Dye
Pigment
OEM vs Compatible

8. The need for coated paper
Inkjet coating
PE coating
Base 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

9. Pigments stay (mainly) on the surface & cause diffuse reflection
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! Poor contrast (D-Max) Banding Metamarism
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. Photo Editor Application
Printing Software
Photo Editor Application
Printer Driver
PC/Operating System

17. Colour Management Non-managed printing Colour Managed
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 Print 6MB photo at 250 ppi
Resampled to internal resolution (600 ppi)
Data (35MB) transmitted via USB connection
Outputs ink droplets at 2400 dpi
Photoshop/Elements
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 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
Qimage
Qimage
Qimage
Qimage
Qimage
Qimage
Qimage
Qimage
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…