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I recently did some sample prints with my new photo printer and some photo paper. I didn't like the results, apparently I need to calibrate it. I haven't been able to find any ICC profiles for that printer + that paper (both Canon, btw), so I will need to invest some time and money.

There are several options, like buying a IT8 chart and some scanner software, print a testchart and scan it again or download a testchart, print it and send it so some lab so that they can create that ICC profile for me.

But the big question is: There are test charts with a few hundreds up to several thousands of colors. IT8 has only 290 samples (266 colors + 24 greys). How many color samples do I really need? Does it make sense to calibrate a printer with 1000 samples if the scanner can only be calibrated with 290 samples? Or do labs calibrate their scanners with more samples, so that they are really able to provide that higher accuracy?

Even then, if I don't want to print high quality fine art, how many samples are enough?

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    Doesn't Canon have the appropriate profiles on their website? If both the printer and paper are Canon, I'd expect them to make a profile available. Doing a quick web search turns up several pages on their web site about printer profiles. – user1118321 May 6 '17 at 15:55
  • I would have expected the same, but apparently they only offer ICC profiles for the professional line of printers. This was already discussed here: photo.stackexchange.com/questions/50610/… – craesh May 6 '17 at 16:22
  • Does the printer driver have a setting that disables driver based color management? Profiles should be used, and generated, with the printer driver color management disabled. This is how profiles work with "professional" printers. If you tell us the model of the Canon printer we may be able to provide specific advice. As an aside, scanners don't generally make very good profiles. First, you have to calibrate them but that only works if the target you calibrate them to has the same spectral properties as the printer. They rarely do. – doug May 6 '17 at 19:15
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    This is all heavily dependent upon the specific printer and how many and what types of inks it uses. Since you've chosen to not disclose the printer model we have no way to answer your question. The answer will be different for a printer using a basic four ink system and one using multiple shades of cyan, magenta, and yellow as well as multiple black and gray shades. – Michael C May 6 '17 at 19:16
  • The printer is a Pixma MX925, that includes a scanner. But finally I have found a setting where I can set up the media type, the Canon's paper I am using is included there. It was hidden from the print dialog, that's why I thought this wasn't possible. The result is OK, but still a little bit off my expectations (my Display is calibrated, btw). But I haven't been able to find an option to disable these included color profiles. – craesh May 6 '17 at 20:20
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Having worked on generating ICC profiles some years back...

First, profiles and calibration are separate things. Calibration means making sure that you get a consistent output for a given input (for output devices) or vice versa for inputs.

There's no point in trying to generate a profile for an inconsistent process. Once you've calibrated it, THEN you can think about profiling it. Note that for output devices, you're really profiling the WHOLE output process - printer, media, inks, enviromental conditions, drying process, etc.

For profiling output devices, professionals use devices called spectrophotometers. These measure the printed output (after it's had time to dry properly) by measuring the reflectance of each patch at many different wavelengths. This lets the device work out an accurate XYZ tristimulus value - basically, an accurate way of measuring what the printed colour looks like under standard illumination.

Then the clever bit takes place - knowing what the printed patches look like, for a given set of input values, the profile generation software can work out what values to feed to the printer to end up with a desired colour.

How many patches you need depends on how good the profile generating software is, and how well it models interactions between different channels.

more patches allow for dumber models, or better information for clever models.

  • Unlikely that the OP's printer has any mechanism at all to calibrate the printer since they don't even provide profiles for it. Even for prosumer printers that provide profiles there is no calibration. You just use the paper and quality settings specified in the instructions on using the profiles. IT8 charts are not used for profiling printers. They are for scanners or cameras, a completely different process. Cheapest way to get a printer profile is to buy one. The vendor will send test chart(s) to print. Then you send them back and they email a profile, – doug May 6 '17 at 21:02
  • Yes - for consumer printers, the closest to calibration is probably using the same inks and media. Fortunately, there's not a huge variation between printers of the same type, so often the profile from the manufacturer does a decent job - but a custom profile for the specific printer may do better if there's any variation. Or if you're using different media or inks, you may need a custom profile. – JerryTheC May 6 '17 at 21:14
  • And yes, you're quite right about the IT8 charts. From memory (it's been several years) they come with a set of reference measurements (again, usually from a spectrophotometer) so you know what the original colours were, and can then do a similar calculation from the scanned channel values. If the chart fades over time, you've got problems unless you can remeasure it. – JerryTheC May 6 '17 at 21:19
  • Yes, the IT8 comes with spectro readings. I think a CGATS file. That's useful for profiling a camera where the illuminant isn't D50. Otherwise, if you only have XYZ values you need to be reasonably close to D50 since invariably that's the illuminant XYZ values were computed from. In any case printers are profiled with a set of untagged RGB values. The patches are read with a spectro and profile generated. Best done by one of the labs that offers the service. If you have a lot of paper/printer combos that gets expensive and time to get an X-rite (or similar) solution. – doug May 7 '17 at 3:37
  • True that I can only calibrate/profile a scanner with a IT8 chart. But the idea is to first calibrate the scanner, and in a second step do a couple of iterations printing testcharts and scanning them again, with adjustments in between. Those labs where you mail in your test chart don't do anything else, except that they only need one iteration. But again: How well do they calibrate their scanner? Do they have anything better than IT8 charts with "only" 290 samples? – craesh May 7 '17 at 8:37

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