Isetbio and retinal images

[DavidBrainard]

Dear Prof. Brainard,

my name is Kristof Meding, I am a PhD student in Felix Wichmann’s lab at the University Tübingen in Germany.

I have developed software for calculating retinal images based on peripheral wavefront data in my Masterthesis. In brief, I got peripheral wavefront aberration sensing data form Pablo Artal, calculated Point-Spread-Functions together with blurred image patches across the visual field and used an algorithm to combine these patches into a single image.

Felix told me about the discussion he had with you about the isetbio-package and retinal image simulation at VSS. This is of great interest for our own research. In particular, I have three specific questions which I would be grateful if you were able to help me with:

1. The isetbio-package has a function to calculate PSFs from the Artal et al. 2012 horizontal dataset. Does this include the possibility to calculate a single horizontal image from -40 to 40 deg?

2. Isetbio offers the possibility to calculate retinal images for the periphery with ray-tracing. Did you compare (for the periphery) the output of the ray-tracing methods with calculations from wavefront sensing data, e.g. PSFs obtained from both methods?

3. Are chromatic aberrations calculated only with the accommodated Navarro model?

Best regards from Tübingen

Kristof Meding

[DavidBrainard]

Hi,

Posting this here so that others on the isetbio team can see and chime in.

1. No, we don't have something that would stitch together patches into a single image with position dependent blur.

2. The ray tracing is mainly the work of Trisha Lian. I believe she is working on comparisons of this sort, but that they do not exist yet.

3. No, we compute chromatic aberrations using the wavefront data, by adding wavelength-dependent defocus as part of computing the pupil function. Separately, LCA is included in Trisha's ray tracing model.

[tlian7]

Hi Kristof,

If you are interested in learning more about producing a retinal image using ray-tracing, I'd be happy to chat or answer any questions you have.

@DavidBrainard has pretty much answered your questions, but just to expand:

(1) With ray-tracing, it is possible to create a single retinal image across a range of eccentricities. (2) However, I am still currently in the process of comparing the outputs of ray-tracing with those from the wavefront data. Roughly speaking, we would expect that the performance would be similar/identical to the performance of the schematic eye model used, in this case, the Navarro eye model. You can find a general overview of its off-axis performance in the following paper (although this analysis was done pre-wavefront sensing era.) We do also have the flexibility to implement other schematic eye models as well, though this depends on the complexity of the model. I will keep you updated on our wavefront comparison analysis. (3) Like David said, LCA and TCA is naturally modeled within the ray-tracing as well.

Hope this helps!

Trisha

[DavidBrainard]

Agree with Trisha's amendment to my response on point 1. What I meant referred to what we can currently do with the wavefront PSFs.

I should also add we are eager for community contributions to ISETBio. So if you start using it and have improvements or bug fixes, please don't hesitate to issue a pull request and we'll try to integrate them in.

[ghost]

Dear Prof Brainard, Dear Trisha,

thank you very much for your effort in answering my questions. A comparison between wavefront and ray-tracing models would be very interesting for us. I’ll have a look at the ray-tracing methods.

Best

Kristof

[DavidBrainard]

Let us know if you get stuck, we're happy to help. Closing this issue, for now at least.