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Author Topic: i1isis / i1isis 2 aperture size?  (Read 601 times)

smilem

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i1isis / i1isis 2 aperture size?
« on: May 30, 2018, 05:28:17 PM »

Hello, can anyone give me a hint on the size of scanning aperture of 1isis?
Has it changed on i1isis 2 or both are the same?

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Doug Gray

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Re: i1isis / i1isis 2 aperture size?
« Reply #1 on: May 30, 2018, 05:46:43 PM »

Hello, can anyone give me a hint on the size of scanning aperture of 1isis?
Has it changed on i1isis 2 or both are the same?

The effective aperture is about 5 square mms for 90% of the reflected light or about 15% of the surface of a 6mm by 6mm min. size patch. I measured this in both horizontal and vertical directions on my Isis2 XL and posted graphs here. I suspect it's the same for the earlier ones.

The horizontal aperture expands as the horizontal patch width increases. The vertical aperture is fixed.

http://forum.luminous-landscape.com/index.php?topic=120928.msg1004316#msg1004316
« Last Edit: May 30, 2018, 05:53:16 PM by Doug Gray »
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Mark D Segal

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Re: i1isis / i1isis 2 aperture size?
« Reply #2 on: May 30, 2018, 05:51:46 PM »

According to the product specifications there is an "effective measurement aperture" which varies depending on the patch size: "Effective measurement aperture during scanning is depending on the patch size". Taken from https://www.xrite.com/service-support/product-support/scanning-instruments/i1isis-2.

This would seem to suggest that what Doug reports above is the maximum aperture?
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Mark D Segal (formerly MarkDS)
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Doug Gray

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Re: i1isis / i1isis 2 aperture size?
« Reply #3 on: May 30, 2018, 05:59:10 PM »

According to the product specifications there is an "effective measurement aperture" which varies depending on the patch size: "Effective measurement aperture during scanning is depending on the patch size". Taken from https://www.xrite.com/service-support/product-support/scanning-instruments/i1isis-2.

This would seem to suggest that what Doug reports above is the maximum aperture?

The minimum effective aperture area is about 5mm sq for about 90% of the light. It expands as the patch length increases but not as the height increases. It appears to add multiple scan slices every .2mm or so horizontally to create an effective scan length that adjusts to the patch width.  The vertical aperture is fixed so there is little point in increasing the vertical spacing other than reducing registration errors that could cause adjacent patches to contaminate readings. I've seen this when using the M0/M1/M2 mode which does a back hitch. Especially with large, 13" x 19"  targets. The inertia of the paper is significant and it's critical to keep the paper flat as if feeds through the scanner. If one end drops of the table just a few inches it can impact scans.

Patches are scanned at a rapid rate over one patch and the horizontal aperture for a single scan is likely quite small. Perhaps on the order of a just 1 mm or less. The vertical aperture is fixed at about 2.5mm.
« Last Edit: May 30, 2018, 06:04:26 PM by Doug Gray »
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arobinson7547

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Re: i1isis / i1isis 2 aperture size?
« Reply #4 on: May 30, 2018, 07:40:43 PM »

Barbieri Electronics (Spectro LFP Series 3) makes it a little simpler.

They have a selectable aperture of 2mm, 6mm or 8mm. That device can also take and average several measurements of a single patch in .1mm increments. But they and their documentation explain that a larger Aperture is much better then averaging (when/if you have the option)


That xrite 'effective aperture size' sounds like 'effective resolution' of printers/scanner (not the real hardware resolution).

https://www.barbierielectronic.com/en/core-competences/variable-measuring-aperture/11-608.html
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Mark D Segal

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Re: i1isis / i1isis 2 aperture size?
« Reply #5 on: May 30, 2018, 07:42:56 PM »

Not to wander too far off-topic, but what does that Barbieri cost compared with an iSis?
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Mark D Segal (formerly MarkDS)
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arobinson7547

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Re: i1isis / i1isis 2 aperture size?
« Reply #6 on: May 30, 2018, 07:51:50 PM »

US9000$
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Mark D Segal

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Re: i1isis / i1isis 2 aperture size?
« Reply #7 on: May 30, 2018, 08:22:25 PM »

Uhuh. So he/she who pays more gets more, no? I believe that Barbieri also accommodates condition M3 for profiling, which is sweet.
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Mark D Segal (formerly MarkDS)
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smilem

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Re: i1isis / i1isis 2 aperture size?
« Reply #8 on: May 31, 2018, 02:25:12 AM »

Thank you for replies, I was asking the aperture diameter in mm.
I looked at the optics of i1isis and there are 2 lenses one larger the other smaller both are about 10mm diameter, but inside I suspect it gets more narrow so the outside measurement can get wrong.

I'm asking for aperture diameter because I want to make charts to ISO 5-4:2009
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Doug Gray

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Re: i1isis / i1isis 2 aperture size?
« Reply #9 on: May 31, 2018, 01:01:12 PM »

That xrite 'effective aperture size' sounds like 'effective resolution' of printers/scanner (not the real hardware resolution).

Unfortunately, the physical aperture is misleading. For instance the I1Pro has a physical, circular, aperture of 4mm. A naïve interpretation from that would be that it's readings are an average of that area or around 12 mm^2. In reality it's measurements are of a much smaller area because what matters is the distribution of illuminance as reflected back and measured by the instrument. My testing of I1Pro's is that the effective area of spot measurements is much smaller, around 3 mm^2. This smaller area exacerbates variation from printer color dot distribution. Ink jets these days are so good that this isn't a significant factor except on very coarse media like canvas. When an I1Pro is used in scanning mode, the distribution is improved because the patches are sampled longitudinally. The wider the patches the lower the measurement variance.

I have no idea whether the physical aperture of Barbieri's devices represents the actual, effective aperture but it's likely to be closer since they specialize in measuring colors on substrates where the actual, effective aperture needs to be larger. Wouldn't be that hard to measure the effective apertures and I would do so if I had one of their instruments but my curiosity is not sufficient to spend the $ and nothing I currently do would benefit.
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smilem

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Re: i1isis / i1isis 2 aperture size?
« Reply #10 on: May 31, 2018, 06:08:00 PM »

i1Pro aperture is not 4mm it's 4.5mm. I was told by rpimaging that same aperture is for isis and isis v2.
Xrite as always - no response.
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Doug Gray

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Re: i1isis / i1isis 2 aperture size?
« Reply #11 on: May 31, 2018, 07:29:06 PM »

i1Pro aperture is not 4mm it's 4.5mm. I was told by rpimaging that same aperture is for isis and isis v2.
Xrite as always - no response.

The physical aperture and the effective aperture mean different things. The physical aperture is the physical area of the opening. The effective aperture is the area, that if illuminated evenly, would provide the same accuracy when measuring irregular media like inkjet dots, canvas, etc. The I1Pro does not evenly illuminate but rather focuses on a very tight circle much smaller than the physical aperture. Over 80% of the measured light from an I1Pro comes from within a 2mm diameter circle which only occupies 20% of the aperture's area.

However, the physical aperture is important in that it must cover the patch else error is introduced from adjacent patches that have very different colors.

In scanning mode the effective aperture is extended along the scanned axis so widening patches can reduce scanned errors except in the case of pattern noise if the pattern also runs horizontally.
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smilem

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Re: i1isis / i1isis 2 aperture size?
« Reply #12 on: June 01, 2018, 01:10:59 AM »

Thanks for explaining, the ISO 5-4:2009 deals with physical aperture.
Therefore patches "circle" must be 2mm larger then aperture.

But why the lens on i1isis is about 10mm? if aperture is 4.5mm? Also there are two lenses, one is a light?

If Xrite would provide specs for their instruments there would be no need for this thread, but instead they call same parameters different for different products, or provide what they like for one product and not for another. :o
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Doug Gray

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Re: i1isis / i1isis 2 aperture size?
« Reply #13 on: June 01, 2018, 01:29:13 PM »

Thanks for explaining, the ISO 5-4:2009 deals with physical aperture.
Therefore patches "circle" must be 2mm larger then aperture.

But why the lens on i1isis is about 10mm? if aperture is 4.5mm? Also there are two lenses, one is a light?
The reason is that spectrophotometers are required to illuminate at 45 degrees and sense at 0.  The lens has to be wide since it must focus the light source down to a relatively small spot with a "funnel" shape hence the relatively small effective aperture. The smaller the aperture the greater the variance is from surface irregularities in color. The physical aperture serves to stop light contamination from adjacent patches since even 1/1000th light leakage from a white patch can raise L* on black ink patches by nearly 1 dE.
Quote

If Xrite would provide specs for their instruments there would be no need for this thread, but instead they call same parameters different for different products, or provide what they like for one product and not for another. :o

Yeah, would be nice if XRite provided more technical info but they don't.
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smilem

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Re: i1isis / i1isis 2 aperture size?
« Reply #14 on: June 02, 2018, 05:06:04 AM »

When there was no isis, only i1pro I wondered why default charts have such small patches not conforming to ISO 5-4:2009.
Because patches needs to be 1.08cm x 0.93cm to be ISO 5-4:2009 compliant.

If i1isis used same 4.5mm aperture as i1Pro then that means one should have 1.08cm x 0.93cm patches to be safe.
As you said physical aperture does not let light get contaminated with neighboring patches.

Making targets not compliant to any standards is another bad thing about xrite. By making cheap products like colormonkey they clearly showed that they think we are monkeys nothing more, nothing less. And people still continue to buy them.
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Mark D Segal

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Re: i1isis / i1isis 2 aperture size?
« Reply #15 on: June 02, 2018, 08:59:42 AM »


Making targets not compliant to any standards is another bad thing about xrite. By making cheap products like colormonkey they clearly showed that they think we are monkeys nothing more, nothing less. And people still continue to buy them.

While I have issues about X-Rite (who doesn't) I'd be surprised if the situation were as simple and simplistic as you are portraying it. Not every one who wants to take control over their colour management can afford to buy an iSis or even an i1Pro kit. So to the extent there is a market for a less expensive solution, and companies like X-Rite are prepared to supply it with innovative solutions, so be it. While these solutions may be innovative and less expensive, they may also not be fully compliant with preexisting standards, they lack some of the features of the higher-end products and they may not be quite as accurate in some respects. Be all that as it may, the real questions are whether they perform to the satisfaction of their customers, and how well do their results compare with their more expensive, standards-compliant counterparts. There are several reviews of some of these products worth consulting, but perhaps more of this kind of research and reporting needs to be done. So I'd suggest some care in issuing these blanket condemnations.
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Mark D Segal (formerly MarkDS)
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smilem

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Re: i1isis / i1isis 2 aperture size?
« Reply #16 on: June 02, 2018, 09:59:43 AM »

"So I'd suggest some care in issuing these blanket condemnations."

I would be ashamed if my company were manufacturing specros after merging with gretagmacbeth for few years and not know that different factories have different etalon's and this made the need for XRGA nonsnese. The were covering their asses with new inter instrument agreement standard to make different instrument talk color precisely when in fact they were manufacturing spectros to different etalons.

Sorry for my bad english, but I was referring to "cheap" tools from xrite. I was making a point that even while xrite has a right to offer such tools and this a huge promotion for color management in general. How can they offer such bad support?

I understood bad xrite support back in the 2007 or when did colormunkey got introduced to the market. But now year 2018?

Xrite software is another or yet same story. It is not normal to have to use profilemaker these days, but it target generator is just better then i1profiler. I count decades since merging with gretagmacbeth and we still have no proper software package. While colorport was promising it was discontinued, I wonder why?

The software scene is so absurd that third party vendors like chromix curve4, basiccolor etc. have made their own spectro drive features so you don't have to use xrite.
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Mark D Segal

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Re: i1isis / i1isis 2 aperture size?
« Reply #17 on: June 02, 2018, 10:15:30 AM »

Support is a different story from what you were talking about, and there are support issues with X-Rite, but another talk show.

As for BasicColor - it's an independent company offering their own suite of (high quality) colour management products. No reason why they should be hitched to or dependent on X-Rite for anything. Chromix is offering a different kind of product line, so yes their software architecture would be their own as well. Nothing to do with X-Rite qualities or defects.

Lots of confusion here.

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Mark D Segal (formerly MarkDS)
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digitaldog

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Re: i1isis / i1isis 2 aperture size?
« Reply #18 on: June 02, 2018, 04:12:09 PM »

I would be ashamed if my company were manufacturing specros after merging with gretagmacbeth for few years and not know that different factories have different etalon's and this made the need for XRGA nonsnese. The were covering their asses with new inter instrument agreement standard to make different instrument talk color precisely when in fact they were manufacturing spectros to different etalons.
XRGA doesn't change how differing X-rite devices behave differently in terms of color measurements. An iSis Rev C and E measure white differently which has zero to do with XRGA. That was simply an unnecessary communication protocol.
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Andrew Rodney
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smilem

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Re: i1isis / i1isis 2 aperture size?
« Reply #19 on: June 04, 2018, 02:36:33 AM »

As for BasicColor - it's an independent company offering their own suite of (high quality) colour management products.

Have you been living under a rock?
Yes basiccolor offer products with their logo, but they license most of the main stuff from colorlogic.de

Colorlogic copra -> basICColor print
Colorlogic colorant -> basICColor improove
Colorlogic zepra -> ghost

Now even basiccolor stated that "…the gHOST becomes a ZePrA" so there you go.

What is wrong with such sales schemes is that basiccolor sells one generation older software then colorlogic has. That is because they get one generation older stuff. So in my eyes basiccolor does not make anything useful they are a reseller.

 
« Last Edit: June 05, 2018, 03:02:37 AM by smilem »
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