I have a HP 9180. I would like to make digital negatives for alternative printing with this printer using the Grayscale Mode and selecting printing with the gray pigment inks only. However, when I select these modes the Ink Density setting becomes inoperative. I have found this to be the case using both printer based and application based color management.

Does anyone know of a mode and setting that will keep the Ink Density setting operative when printing in Grayscale using only the gray inks?

Sandy King

In OEM drivers there's no way to control 100% black ink density other than selecting different media profiles (paper settings) in the driver. With that you can find a paper setting that will have a higher ink limit and by that more light blocking at 100% black. There could be detail loss at 100% black caused by ink bleeding though. In reflective density measurements a higher inkload isn't always delivering a higher Dmax, at some point that usually doesn't increase. But we are talking digital negatives = opaqueness for negatives here.

The controls available in OEM drivers are gamma controls and will influence the ink load between film transparency and 100% black but will not have an influence on the 100% black. You could do the gamma correction or complex curve corrections on the image in Photoshop with the curve feature more precisely than in the printer driver and save the curve. If there's an advanced B&W menu in the B9180 driver you might find gamma control there, like it is available in the Z3100 driver that I know.

There have been discussions about the use of pigment or dye ink and using CMY inks as well for blocking actinic light in alternative processes. The Kkk pigment inks may not be the best choice, depending on the light source.


Ernst Dinkla

try: http://groups.yahoo.com/group/Wide_Inkjet_Printers/

Hi

I don't have this printer but in theory an ink density button should add equal amounts / balanced amounts of CMY so that your images have more density, hopefully without changing the colour. A rough GCR tool, if you like.

As you have selected to print with the blacks/greys only, the CMY heads are not available to you to add the extra density.

In the HP driver, ink levels are in-built to the basic paper choices you are given - try different paper types to see which ones give more ink density.

The only way to control this otherwise is with a third party RIP I'm afraid.

What I want to do is decrease, not increase, the maximum UV transmission density, and hoped to do so by adjusting the ink density of the gray inks. With my current settings I using application based color management and printing with Grayscale Color Management. With the inks set to gray inks only, I get a maximum UV transmission density of about log 3.25, or log 3.05 (substacting the UV transmission of the OHP substrate). What I would like to do iis decrease the density of the gray inks to drop the mximum density to about 2.00 - 2.20 (minus the substrate). If I understand correctly, this can not be done with the printer drivers but only with media setting? So is there a way of knowing without testing which media settings use less ink?

I have already determined RGB colors that produce spectral density negatives of the correct transmission density for UV sensitive alternative processes. There are in fact several different combinations that work well. The issue is finding the one that prints the smoothest with UV processes so I wanted to compare a negative made with composite black to one made with only the gray inks, and to compare both to the spectral density negatives.

Sandy King

Sandy,

Decreasing will not be a problem, my guess has been wrong that you wanted to increase the black density. Finding the right media setting shouldn't be necessary, the Photoshop curve tool should be sufficient to pull down the 100% K to approximately 68% in the image or a similar shift in the B9180 Advanced B&W driver mode if it allows you to pull down the 100% K too and isn't just a gamma comtrol.

Wonder whether you will find much difference between RGB composite grey selections and using the grey inks if you kept the RGB selections near the neutral spine, the long black generation with more grey inks in a color printer will substitute composite grey with grey inks anyway. In that case smoother results at 2.2 transmission dynamic range are probably easier to get by shifting a monochrome grey image to monochrome cyan. Which can also be done in the Advanced B&W mode of the driver. Only theory on my side.

Pity that QTR doesn't support the HP models, it suits this kind of work best.

Ernst Dinkla

try: http://groups.yahoo.com/group/Wide_Inkjet_Printers/

Ernst,

I adjusted the curve in Photoshop until the maximum UV transmission density was about log 2.2, more or less what I wanted. This was with color managment set to Grayscale and printing with only the gray inks. For some reasons this setting caused a lot of banding and a very grainy looking negative. By contrast, printing an RGB file in grayscale with the composite black gives a maximum transmission density of about 2.27, and visually it is very smooth with no banding.

Sandy

Though I didn't expect banding I thought it would be grainier. In RGB and with composite grey not replaced by grey ink (so not a long black generation) you will get three softer tone droplets LC,LM,Y or CMY covering a wider area than the one hard grey or black droplet that replaces the same tone in greyscale printing. More or less similar to how collotype is smoother printing than an offset halftone plate. If HP would replace the CMY droplets with a grey ink of related density it wouldn't reduce inkload and reducing inkload to some degree has many advantages.

The B9180 has the same inkset the Z2100 has, correct? If you also reduce the tonal range to 2.2 your negative most likely will use one grey ink mainly and hardly the photo black. It could be that the tonal range compressed can't find enough nuances in dot expression of one grey ink and by that is prone to banding = more a clustering of tone steps to the same dot density, another possibility: the one grey ink dot distribution gets so stretched in the stochastic pattern printing that it shows, on thin ice here. Printing on film usually gives very well defined round dots, that adds too.

There's also the droplet size difference of 4 and 6 picoliter per ink hue and grey inks that may play a role here. I do not know how that is on the B9180 but for example the MK,C,M,Y, on the Z2100 are squirted as 6 picoliter droplets, the LC, LM, LG and PK as 4 picoliter droplets. That emphasises the hard core density of a 4 picolitre grey or black droplet on a transparant area of film even more compared to 3 CMY droplets of 6 picoliter size on the same area. Depending on where the partioning between the lighter and darker inks happens you will notice differences in grain variation. Check it with a microscope.

If smoothess is the most important factor then you better skip grey inks on the B9180. I'm not even sure whether a cyan or red bias in color printing then would make better smoothness, could be that an even distribution of LCLMYLG + CMYK droplets is better than taking out LG and K in the mixes. In other words: reducing black generation by coloring the image may not be better.

Ernst Dinkla

try: http://groups.yahoo.com/group/Wide_Inkjet_Printers/

Ernst,

Thanks for your comments about the way the ink drops are distributed. The theory has been quite useful to me in understanding this issue.

Smoothness is indeed the most important factor. However, what counts is not just visual smootness, but amoothness printing on a specific process with UV light.

Eventually I matched maximum UV transmission density with three colors: composite black, Red, where R = 255, G= 0 , B = 10, and Green, where G = 255, R = 70, B= 0. All three gave maximum UV density of about 2.0, subtracting the substrate.

I then printed three 101 steps transmission wedges on OHP, and when dry, used the three wedges to expose palladium step wedges. What I found was that the Red step wedge was quite a bit smoother than the Green wedge, and just a tad smoother than the composite black.

So what I have found is that for my purposes there is no need to be concerned about the premise of the original thread since I don't need to use the gray inks anyway, except perhaps in composite black where the ink density setting are operative anyway. But thanks for the comments since I learned a lot on the way.

Sandy King

That's the only way to figure out what a color shift could add. Too much related to the spectral aspects of all the steps in the process to approach it theoretically.

Will try to remember this but I doubt that I will ever use it.

Ernst

try: http://groups.yahoo.com/group/Wide_Inkjet_Printers/

You are absolutely right. The spectral issues are very complicated and direct tests are the only way to know for sure how a digital negative will print with UV processes. One can not even be sure that different colors that measure the same in terms of density range will print with equal contrast. In the present case the green negative printed with much less contrast than the composite black and red negatives, even though all three measured almost identically with a UV densitometer. I could speculate on why this might be in terms of the bandwidith of the densitometer and the sensitivity of the process, but in the end only direct tests provide certain information.

Sandy King