Help with creating locations of a regular pattern

[Jbryant61]

I have create a set of random locations and then at each location I place an object to simualte an image.

The delta just makes sure no objects are within 3 pixels of the image edge.

I know want to be able to change the locations now to represent the following regular pattern. I believe horizontallt there is a pitch of 8 pixels, and vertically a pitch of 9 pixels with a horiztonal shift of 4 pixels.

Thnaks for any help

Jason

[RichardJ]

Something like this?

[Jbryant61]

Thanks Richard - its a while since we last spoke on this forum!!

Please see the attached, you  helped me before a couple of years ago place a point spread function of random amplitude at each of these locations.  I have tried to combine your previous work with this patterned location array and nearly have it, there's 3 issues that have arisen though and I'm not sure how to do them.

In particular:

1: How to count the number of objects, I tried the following but its not right.

2: How to apply random amplitudes to the objects  using

    amp=runif(n,0.1,1)         - but how to then apply it to the objects in M?

3: How to get rid of the strange edge effect ont he right hand side

and lastly, how to allow for a random 0.5 pixel shift so that each psf is not necessarily centred exactly on a pixel.

Thanks

Jason

[Jbryant61]

I've managed to answer my own questions, not sure if its the most elegant way.  I included the randomw amplitude and object count in Richards original function.

Im still getting a strange edge effects on the RHS once its convolved with the psf.

Jason

[RichardJ · Accepted solution]

Use the built-in convol2d function and the edge effect goes away (i could probably get it to go away using FTs as well, but the built-in function is a lot easier!).

[Jbryant61]

Thansk Richard

[Jbryant61]

Is it easy to modify this so the distance between the centres in x and y can be changed?   i.e. I need a pitch of 6pixles in x, and 5 pixels in y.

Thanks

Jason

[RichardJ]

Sure. I was lazy, so this only has one pitch value, but you can easily modify it to have different pitches for x and y.

[Jbryant61]

Thanks Richard. I think I've nearly done it, there just seems to be an issue of padding in the final array. Any suggestions please.

Thnaks

jason

[RichardJ]

Do you want to remove the bit at the bottom (i.e. the aspect ratio of the image will no longer be 1:1), or do you want to fill it with more pattern?

[Jbryant61]

Yes remove the bit at the bottom, so no longer have aspect ratio of 1:1.

Thanks

Jason

[RichardJ]

Remove the first line of the program.