Skip to content

Commit

Permalink
Some Corrections and Deletion of Slides
Browse files Browse the repository at this point in the history
  • Loading branch information
ShrayanRoy committed May 21, 2024
1 parent 4c326e2 commit 8101c13
Show file tree
Hide file tree
Showing 2 changed files with 12 additions and 54 deletions.
33 changes: 6 additions & 27 deletions presentation/finalpresentation.Rmd
Original file line number Diff line number Diff line change
Expand Up @@ -34,7 +34,7 @@ xaringanExtra::use_panelset()
```


# Depth Estimation
# Depth: the third dimension

* Traditional photographs are two dimensional projections of a three dimensional scene.

Expand Down Expand Up @@ -94,27 +94,6 @@ $$k(x,y) = \frac{C_{h,r}}{2\pi h^2} e^{-\frac{x^2 + y^2}{2h^2}} \times \text{I}_

$$k(x,y) = \frac{C_{h,r}}{2\pi}\frac{h}{(x^2 + y^2 + h^2)^{3/2}}\times \text{I}_{\{x^2 + y^2 \ \leq \ r^2\}}$$

---

# Image Blurring Model

* The blurred image can be viewed as **convolution** of original sharp image and blur kernel.

* The observed blurred image $\boldsymbol{b}$ can be modeled in terms of its gradients $\boldsymbol{x}$ as -

$$\boldsymbol{y} = \boldsymbol{k} \ \otimes \ \boldsymbol{x} \ + \ \boldsymbol{n}$$
Where,

* $\boldsymbol{k}$ is blur kernel and $\boldsymbol{x}$ is gradient of *true latent image*.

* $\boldsymbol{n}$ is gradient of noise and $\otimes$ denotes the *valid convolution* operator.

* Expressing the model in frequency domain as -

$$\boldsymbol{Y_{\omega} = K_{\omega}X_{\omega} + N_{\omega}} \ \ \ \forall \ \boldsymbol{\omega} = (\omega_1,\omega_2)$$
* We assume Nandy's Auto regressive prior on DFT coefficients $\boldsymbol{X_{\omega}}$.


---

# Maximum Likelihood Estimation of Blur Kernel Parameters
Expand Down Expand Up @@ -234,21 +213,23 @@ knitr::include_graphics("pimg/couple.png")

# Challenges in Post-Segmentation ML Estimation

* Our ML estimation procedure requires images of rectangular shapes.
* ML estimation procedure requires images of rectangular shapes.

* But image segments obtained by SAM are of irregular shape.

--

* Obvious solution is to pad or fill with zeros to make rectangular array.

* This approach leads to bias towards selecting small values of radius $r$.

```{r ,warning=FALSE,echo=FALSE,out.width='60%',out.height="40%",fig.align='center',echo=FALSE,fig.cap= "Figure: Zero padding to make rectangular array"}
knitr::include_graphics("pimg/zero_pad.png")
```

--

* This approach leads to bias towards selecting small values of radius $r$.

---

## Experiment
Expand Down Expand Up @@ -309,8 +290,6 @@ knitr::include_graphics("pimg/ap1.png")

* Apply estimation procedure to these sub regions.

--

* Discards a large proportion of available data depending on how irregular segment it is.

```{r ,warning=FALSE,echo=FALSE,out.width='70%',out.height="30%",fig.align='center',echo=FALSE,fig.cap= "Figure: Irregular segments identified by SAM"}
Expand Down
33 changes: 6 additions & 27 deletions presentation/finalpresentation.html
Original file line number Diff line number Diff line change
Expand Up @@ -44,7 +44,7 @@
</style>


# Depth Estimation
# Depth: the third dimension

* Traditional photographs are two dimensional projections of a three dimensional scene.

Expand Down Expand Up @@ -101,27 +101,6 @@

`$$k(x,y) = \frac{C_{h,r}}{2\pi}\frac{h}{(x^2 + y^2 + h^2)^{3/2}}\times \text{I}_{\{x^2 + y^2 \ \leq \ r^2\}}$$`

---

# Image Blurring Model

* The blurred image can be viewed as **convolution** of original sharp image and blur kernel.

* The observed blurred image `\(\boldsymbol{b}\)` can be modeled in terms of its gradients `\(\boldsymbol{x}\)` as -

`$$\boldsymbol{y} = \boldsymbol{k} \ \otimes \ \boldsymbol{x} \ + \ \boldsymbol{n}$$`
Where,

* `\(\boldsymbol{k}\)` is blur kernel and `\(\boldsymbol{x}\)` is gradient of *true latent image*.

* `\(\boldsymbol{n}\)` is gradient of noise and `\(\otimes\)` denotes the *valid convolution* operator.

* Expressing the model in frequency domain as -

`$$\boldsymbol{Y_{\omega} = K_{\omega}X_{\omega} + N_{\omega}} \ \ \ \forall \ \boldsymbol{\omega} = (\omega_1,\omega_2)$$`
* We assume Nandy's Auto regressive prior on DFT coefficients `\(\boldsymbol{X_{\omega}}\)`.


---

# Maximum Likelihood Estimation of Blur Kernel Parameters
Expand Down Expand Up @@ -232,21 +211,23 @@

# Challenges in Post-Segmentation ML Estimation

* Our ML estimation procedure requires images of rectangular shapes.
* ML estimation procedure requires images of rectangular shapes.

* But image segments obtained by SAM are of irregular shape.

--

* Obvious solution is to pad or fill with zeros to make rectangular array.

* This approach leads to bias towards selecting small values of radius `\(r\)`.

<div class="figure" style="text-align: center">
<img src="pimg/zero_pad.png" alt="Figure: Zero padding to make rectangular array" width="60%" height="40%" />
<p class="caption">Figure: Zero padding to make rectangular array</p>
</div>

--

* This approach leads to bias towards selecting small values of radius `\(r\)`.

---

## Experiment
Expand Down Expand Up @@ -307,8 +288,6 @@

* Apply estimation procedure to these sub regions.

--

* Discards a large proportion of available data depending on how irregular segment it is.

<div class="figure" style="text-align: center">
Expand Down

0 comments on commit 8101c13

Please sign in to comment.