##################################################################### Charles, Thanks for posting your problem .par/.frm's 'in public' on [Fractint]'s email list serve:0 At some magnifications the apparent high count areas disappear and at other magnifications they are massively messed up. And Jonathan, Thanks for posting your response publicly on [Fractint]: These PARs need to have periodicity adjusted. Using either 0 or 10 will work. If that doesn't fix the problem you are seeing, let me know. I have always wanted to see an example of a fractal that was sensitive to whether periodicity= was specified and what values of periodicity were useful. Charles, I tried all your fractals with both no periodicity= and periodicity=0 and 10 to see what the effects were of changing this parameter as Jonathan suggested. It would seem that the default periodicity (I think I remember that it is around 3) works to speed up many fractals, but does not work for a few -- like yours. When I created your fractal InandOut with periodicity=0, I observed that there were black ovals in it. I have previously learned that these can sometimes be areas where the iteration limit (511 in your fractal) has been exceeded. When I increased the iteration limit (3rd line on the 'X' parameter page) to 5110 the black ovals filled in, confirming my conjecture that these were 'under-iterated' areas. I was not able to detect a slowdown in the speed that the fractal was created, because so few pixels had iterations higher than 511. Besides, raising the iteration limit fills in more pixels with colors other than black and so gives what seems to me to be a more 'complete' fractal. Your particular color map (most easily seen by typing <E> and then <Enter> while viewing your fractal) has so much yellow that I thought that it might not allow some detail in the oval areas to be seen, now that the pixels in this area were actually being calculated. To see if there was structure in the ovals I loaded a different color map, TOPO.MAP (<L> while in the <E> color 'Palette Editing' utility). Sure enough, there were the multiple copies of the 512 entry TOPO color map repeated in the spiral now in the oval areas as the spiral 'wound' inward. This repeating of the color map shows that more than 512 iterations took place in the oval areas. Section 8.2.1 "Periodicity Logic" in the Fractint 20.0 Documentation gives a pretty good explanation of what Fractint's periodicity feature is and the speedup it can do for you. In that discussion "in the lake" refers to the "inside" color of zero iterations, often colored black or blue. But you have happened by chance to be calculating a fractal that is sensitive to the default value of periodicity in Fractint and needs to have this parameter adjusted. As Jonathan suggested, periodicity=0 or =10 seem to work well for your fractal. In Damien M. Jones Windows tips in the Fractint 20.0 Docs I also note his: "Holes" in an image while it is being drawn: Little squares colored in your "inside" color, in a pattern of every second square of that size, in solid guessing mode, both across and down (i.e., 1 out of 4), are a symptom of an image which should be calculated with more conservative periodicity checking than the default. See the Periodicity parameter under Image Calculation Parameters (p. 116). I'm sorry if I am belaboring common knowledge, but for me when I learned the practical aspects of underiterated fractals, and the sensitivity of fractals to color maps, they were powerful revelations that allowed me to improve my fractals greatly. Jonathan, Thanks for helping me understand the correct use of the periodicity= parameter. - Hal Lane ######################### # hallane@earthlink.net # ######################### #####################################################################

Message: 5 Date: Thu, 08 Mar 2007 21:56:42 -0500 From: Charles F Crocker <chasc@pop.gis.net> Subject: [Fractint] GIF File format To: Fractint and General Fractals Discussion <fractint@mailman.xmission.com> Message-ID: <4.2.2.20070308214642.02d1c6c0@pop.gis.net> Content-Type: text/plain; charset="us-ascii"; format=flowed

Where in a Fract???.gif file does the Fractint data appear? I have a question and want to be on sound ground before I raise it. All I can identify is that the file starts with GIF98a and near the end there is a little plain text that is "fractint001 Fractal" with the space actually being y with an umlaut over it. Nothing else identifiable as plain text. The point I particularly want to know about is how the V screen parameters are included.

My Fractint computer had a disastrous breakdown a couple of months ago and am trying to recover and also evaluate ver 99. I ran across a floppy disk that was labeled "Problems" and am passing along one of them.

Here is my Newpar.par file which includes the formula. The original parameter file was run on Fractint 99 and then recorded again. It doesn't show as much of the problem that showed originally but as you zoom in amazing things happen. At some magnifications the apparent high count areas disappear and at other magnifications they are massively messed up.

Start parameter file.

Julia { ; Parameter file recorded on Win 98 system in DOS mode ; Version 2002 Patchlevel 3 ; Only a trace of original problem ; Fractint Version 2099 Patchlevel 8 ; Fractint Version 2099 Patchlevel 8 reset=2099 type=julia4 passes=1 center-mag=6.199e-006/-2.265e-006/2.109716 params=-1.0296017527580259/0.19608962535858149 float=y maxiter=4097

colors=00000000z<3>PPzVVz``z<3>zzzzzzzzzz00z00<4>zS0zY0zc0<3>zz0<227>zz0 }

Problem { ; Zoom on high count area. ; Version 2002 Patchlevel 3 ; Fractint Version 2099 Patchlevel 8 ; Fractint Version 2099 Patchlevel 8 reset=2099 type=julia4 passes=1 center-mag=0.42653/0.312698/17.29275 params=-1.0296017527580259/0.19608962535858149 float=y maxiter=4097

colors=00000000z<3>PPzVVz``z<3>zzzzzzzzzz00z00<4>zS0zY0zc0<3>zz0<227>zz0 }

InandOut { ; After various zooms. ; Version 2002 Patchlevel 3 ; Fractint Version 2099 Patchlevel 8 ; Fractint Version 2099 Patchlevel 8 reset=2099 type=julia4 center-mag=0.427258/0.296879/9.281967/1.0001 params=-1.0296017527580259/0.19608962535858149 float=y maxiter=511

colors=00000000z<3>PPzVVz``z<3>zzzzzzzzzz00z00<4>zS0zY0zc0<3>zz0<227>zz0 }

frm:julia4 {; Chuck Ebbert added 13 Jan 1993 ; p1=Parameter (default (.6,.55) ) ; bailout is real(p2) (default 4) ; force c=(.6,.55) if p1=0 z = pixel, c = ((0.6,0.55) * (|p1|<=0) + p1 ) t = (4 * (real(p2)<=0) + real(p2) * (0<p2) ): z = sqr(z*z) + c |z| <= t }

End parameter file.

Charles

------------------------------

Message: 6 Date: Thu, 08 Mar 2007 21:34:24 -0600 From: Jonathan Osuch <osuchj@avalon.net> Subject: Re: [Fractint] GIF File format To: Fractint and General Fractals Discussion <fractint@mailman.xmission.com> Message-ID: <1173411264.3906.10.camel@linux.site> Content-Type: text/plain

Charles,

...

Where in a Fract???.gif file does the Fractint data appear? I have a question and want to be on sound ground before I raise it. All I can identify is that the file starts with GIF98a and near the end there is a little plain text that is "fractint001 Fractal" with the space actually being y with an umlaut over it. Nothing else identifiable as plain text. The point I particularly want to know about is how the V screen parameters are included.

It should be shortly after the GIF89a, as part of the standard GIF file format. You would need to look at the GIF specification. I don't believe we save any data from the <v> screen in the Fractint specific data segments. There is a very old DOS program called F-DATA by Marc Reinig, that can extract Fractint specific data from GIFs. It is not up-to-date so it won't see new parameters, but it is real good with the basics. I suspect if you would like to use it I'll have to email it to you, since a Google search didn't find it.

...

My Fractint computer had a disastrous breakdown a couple of months ago and am trying to recover and also evaluate ver 99. I ran across a floppy disk that was labeled "Problems" and am passing along one of them.

Here is my Newpar.par file which includes the formula. The original parameter file was run on Fractint 99 and then recorded again. It doesn't show as much of the problem that showed originally but as you zoom in amazing things happen. At some magnifications the apparent high count areas disappear and at other magnifications they are massively messed up.

***************************************************************************

********

These PARs need to have periodicity adjusted. Using either 0 or 10 will work. If that doesn't fix the problem you are seeing, let me know.

Jonathan

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