[argyllcms] Re: DTP41/T transmissive mode - problems getting good strip reads
- From: Doug Private <doug17r@xxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Sat, 19 Nov 2011 15:36:22 +1100
Could you narrow down a strip that fails, then read the density of the
patches and the separators. It has been reported that the maximum density
difference between the patches and the separators for R, G, or B, must be
at least 0.5. What is you maximum and minimum density?
If you have the necessary density range but targen is not placing the
patches appropriately then try the '-p' argument or manually read a small
chart to make an initial profile and use the '-c' argument.
There are some 'developer' commands you can use to debug the patch reading
on the DTP41, and it may be possible to change the density delta cutoff.
Try:
developerpw - place in developer mode (take care).
17od - shows the strip region processing data.
The 17od command shows 'm_fDensityDeltaCutOff = 0.50'. Not sure if this
can be modified, perhaps one of the configuration parameters 'CF'? Seem
to recall it also shows the number of patches read, or gave some data that
helped debug these issues.
The DTP41 is quite handy for reading transmission charts, and I use it for
ink on diffuse plastic using printtarg, and for 35mm slide film by manually
packing the patches so that the black 35mm frame separator occurs every
four patches.
On Fri, Nov 18, 2011 at 8:08 PM, Ken Conrad <ken@xxxxxxxxxxxxxx> wrote:
> I am making transmission profiles for inks used in transfer printing on
> translucent polyester fabrics. When my DTP41/T (set in transmissive mode)
> is accepting the translucent patches it makes good readings, however at
> least half the strips on Argyll Targen -> Printtarg created targets are
> rejected with "bad reads" (#27 errors). The device does manually read
> single patches ok, but I need to periodically make profiles and manually
> reading 1,000s of patches will take way too long!! I tried reading these
> targets with ToolCrib and ColorPort. The same strips fail, while other
> strips again read good, so I see that the problem is in how the DTP41/T
> rejects or accepts adjacent patch data, then aborts transmitting the whole
> strip's data. I only wish that this 'feature' of DTP41 could be
> overrided....
>
> I have also tried targets created in ProfileMaker and ColorPort, which had
> similar problems. Targen and Printtarg offer much more flexibility and I
> hope, a solution, when I figure out how.
>
> I have read that the DTP41 expects each patch to differ from the adjacent
> patch by a 'density of at least .5' Is it the same for the DTP41/T? What
> type of density is this, Status T, Standard I or ...? Perhaps this transfer
> printing has a lower density range so the DTP41 is rejecting patches that
> would be fine when printed on paper and measured via spectral reflectance.
>
> I can use Toolcrib to make reflectance and transmission density (VCMYRGBO)
> readings of the same strip, but don't know what to look for to compare the
> data sets. Could the appropriate density data comparison for the DTP41 lead
> a way to modifying a section of Printtarg code so that I can print targets
> to fabric that the DTP41/T will like?
>
> Since I'm stuck and my arm is getting really sore measuring individual
> patches.... any advice and help will be gratefully accepted!
>
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