during the first 3D
reconstruction step, so bypassing this issue.
Fun demo- this would be a great exercise for students!
Chuck
From: CCP4 bulletin board <mailto:CCP4BB@JISCMAIL.AC.UK>
on behalf of James Holton <mailto:jmhol...@lbl.gov>
Date: Friday, April 28, 2023 at 11:49 AM
To
Holton
Date: Sunday, April 30, 2023 at 5:16 PM
To: CCP4BB@JISCMAIL.AC.UK
Subject: Re: [ccp4bb] happy/sad maps
Thank you Paul. This is interesting!
I have not played with super-sampling yet. I am assuming you mean
creating a new map 8x the size? If so, did you fill the interstitial
grid with
issue.
Fun demo- this would be a great exercise for students!
Chuck
*From: *CCP4 bulletin board on behalf of James
Holton
*Date: *Friday, April 28, 2023 at 11:49 AM
*To: *CCP4BB@JISCMAIL.AC.UK
*Subject: *[ccp4bb] happy/sad maps
Its still April, but this one isn't a joke.
The smiley-
Dear James,
The questions of optimally combining oversampling, blurring and
de-blurring to obtain accurate approximations of Fourier transforms by
discrete Fourier transform calculations are old hat: they go back to papers
by David Sayre in 1951 ('The calculation of structure factors by Fouri
Thank you Paul. This is interesting!
I have not played with super-sampling yet. I am assuming you mean
creating a new map 8x the size? If so, did you fill the interstitial
grid with zeroes? Local maximum? Linear interpolation? Tricubic spline?
And when you say "sharpen/blur" with a factor
bulletin board on behalf of James Holton
Date: Friday, April 28, 2023 at 11:49 AM
To: CCP4BB@JISCMAIL.AC.UK
Subject: [ccp4bb] happy/sad maps
Its still April, but this one isn't a joke.
The smiley-face electron density in the left panel of the attached image
has the remarkable property tha
what about if you run a 2-D FFT rather than 2-D FFT, if your hand drawing map
in on a 2-D paper?
> On Apr 28, 2023, at 10:48 AM, James Holton wrote:
>
> Its still April, but this one isn't a joke.
>
> The smiley-face electron density in the left panel of the attached image has
> the remarkabl
Its still April, but this one isn't a joke.
The smiley-face electron density in the left panel of the attached image
has the remarkable property that any attempt to sharpen or blur the map
turns it into the frowny-face on the right. If you'd like to try this
yourself, the hidden_frown.map fil
