Difference between CMYK and CMYK + Grey?

[PeterBJ]

You're welcome! Maybe magenta = +20 is better?

 

[andy_48]

Yep, +20 looks about spot on, thanks.

 

[Okks]

I have an ip8750 (used predominantly and regularly for 4x6 snaps but up to A3+ occasionally) and an mg6650 (used for office documents, usually A4, and envelopes etc.). Both printers use the same 3rd party carts and inks from Octoink (which are great, BTW).

I am a rank amateur hobbyist (colour family snaps, mostly, virtually no B&W), have low expectations and am very happy with my setup. They're cheap to run, simple to use and relatively reliable. I used to run a pro 9000 mkII but found it to be overkill for my needs (it was huge and ate printheads if not used regularly).

I've just printed the same B&W image from Lightroom to both printers using Canon paper. Given my very poor expertise, I would claim the 8750 has better greys and the 6650 has more of a slight colour cast. Of course, I can't compare either with a pro printer but I'd be amazed if they could come close!

I've scanned them, for what it's worth, but I think the differences are clear.

It's not very scientific, but I hope this helps.

Thank you for giving it a shot ! That's very interesting because, despite the extra GREY ink, it doesn't looks like there is much of a difference between the two, regarding middle tones.
Does the Canon 8750 B&W print looks really better in real life compared to your mg6650 print ?

Also, if you want to get better BW prints on 8750, they give tips here : https://www.photoreview.com.au/reviews/printers/canon-pixma-ip8760/

 

[andy_48]

Does the Canon 8750 B&W print looks really better in real life compared to your mg6650 print ?

It does to my untutored eye. It's marginal, though, and I'm sure both printers would benefit from PeterBJ's tweaking techniques. Thanks for the link. I've got a lot to learn and try out - I need (another) rainy day!

In any event, I'm very happy with both printers. The 8750 is more aimed at photos and will print up to A3+ (and CDs) whilst the 6650 is an all-in-one office A4 workhorse. I have to say, after just the +20 magenta adjustment, the B&W print from the 8750 was as good as I could hope for. I have to believe that the grey cart helps!

 

[PeterBJ]

The used test colour test image might not be the best to judge printing B/W images if it is converted to B/W by simple desaturation of the colours. The problem is that different colours are not perceived equally dark if in the same strength. Yellow seems a light colour, cyan is a bit darker, magenta still more dark and black of course the darkest. A good conversion must use different "weights" of the colours in the conversion. Try Googling "convert colour images to greyscale" or similar. But this is a very difficult subject, maybe one of our colour and profiling experts could tell more about this?


Edit:

 

[andy_48]

This is a (colour) scan of a 4x6 (colour) print of a B&W test image. I can see a tiny hint of colour in this image that I cannot see in the print. Your trained eye would undoubtedly see things I can't, though!

 

[Ink stained Fingers]

I can see a tiny hint of colour in this image that I cannot see in the print.

oh sure - that's what you can expect - are you using a icc-color profile to normalize your scan output ? Is your monitor
profiled/calibrated to a particular color temperature ?
Even your camera is doing an automatic white balance - AWB - if you don't disable it and control colors otherwise - e.g. in a RAW converter, your scanner is not doing an AWB so the color balance is rather arbitrary.
Your assumed gray print is passing another 2 color filters - the scanner and the monitor - which both tune the output into this or that direction so a tint is unevitable.

 

[PeterBJ]

The limitation with the simple colour adjusting in the driver is that it applies the same correction to all colours. This can be fine for removing a colour cast and improving the print, but for a perfect greyscale individual corrections for individual colours are needed. Profiling can achieve this but is no simple task and takes expensive hard- and software.

 

[drc023]

In all logic, machines using only CMY for color shouldn’t be able to compete with models having an extra photo black cart. In real life though, looking side by side at test images that I printed with a IP3000 (CMY) and a IP4000 (CMYK), I can’t say which is which.

As I was reading comments about CMY vs CMYK printer output I was thinking about the good old days of non-chipped cartridges and when Canon was bundling iP3000 printer rebates with new systems from retailers like Circuit City and selling iP4000 printers for peanuts. I had several of both types so I gave the iP3000's to my daughters. I never did any print for print comparisons, but my girls printed a huge amount of 4x6 prints. I can't say the iP4000 would have done any better, but the iP3000 output was stunning. Even with the refill ink I used in all the printers back then the prints looked very good and haven't shown any noticeable deteriation. I just wonder how much better the prints would have looked had I been using Precision Colors Ink like I do now.

 

[drc023]

Thank you all for your replies, it’s very interesting but I still can’t have a clear answer about my question, how would the difference be seen between two identical images printed using the same paper, same greyscale image printed in greyscale on two different similar printers like Canon pixma 8720 and 6820 which have exactly the same specs execpt one have CMYKK + GREY ink. I’m puzzled by all the reviews online praising expensive 12 inks printers with all the bells and whistles but failing to ever test the advantage of having an extra grey ink for black and white (maybe there is none and it’s just marketing?). Would love to see a side by side somewhere, but nobody tested this!

I thought I could answer your question until I began posting this reply and read your question again. I can give a very unscientific comparison on two and then three other printers, but not CMYK vs CMYK+G. After retiring my iP4000 an MG6220 took its place. That printer uses 6 tanks - CMYK+G and pigment black. The first thing I noticed was b/w prints looked extremely good. I didn't print the same photos as on the iP4000, but the MG6220 output looked great and without the purplish cast as before. Then I decided to get an iP8720. Still using the same cartridge configuration as the MG6220 but with different numbers. While the iP8720 gave output similar to that of the MG6220 I felt the output wasn't quite as good. I also thought the cartridges, PGI-250/CLI-251 didn't lend themselves to refilling as well as other tanks, lots of chip failures. So, I then got a Pro-100 to replace the iP8720. After printing the same images in various sizes up to 13x19 the difference was clear. The iP8720 is sitting sadly on a shelf waiting for a new home. OTOH the MG6220 with its pigment black is noticeabley better with text. FWIW I got two of the MG6220's in 2009 when Canon was dumping them at giveaway prices. The first one has been a workhorse with countless refills being done. The second MG6220 is still boxed up waiting for the first one to expire. I have no estimate when that might be.