Magento: Product Specific View Page

1.- Create a copy of view.phtml in your theme like your_view.phtml
2. change your your_view.phtml as per your requirement.
3.In Your product go to Design tab and inside Custom Layout Update add the following code:

<reference name="product.info">
    <action method="setTemplate"><template>catalog/product/your_view.phtml</template></action>
</reference>

Magento: Show custom image for product collection

foreach ($products as $val) :
    $isNewImage = $val->getResource()->getAttribute('product_name_logo')->getFrontend()->getValue($val);
    ?>
    <a href="<?php echo $val->getProductUrl(); ?>">
        <?php if($isNewImage != 'no_selection'):
            $_newImg ='<img id="your-id" src="'.$this->helper('catalog/image')->init($val, 'product_name_logo')->resize(200, 150).'" alt="'.$this->htmlEscape($this->getImageLabel()).'" title="'.$this->htmlEscape($this->getImageLabel()).'" />';
            echo $_helper->productAttribute($val, $_newImg , 'product_name_logo'); 
        else:
            echo $val->getName();
        endif; ?>
    </a>
    <?php
endforeach;

Codeigniter : Redirect back to previous page

In the page that you want to go back to you can do:

<?php $this->session->set_userdata('referred_from', current_url()); ?>

Then from controller you want to back:

$referred_from = $this->session->userdata('referred_from'); 
redirect($referred_from, 'refresh');