Portfolio in Genesis with Featured Images in a Grid revealing Title and Excerpt on Hover. http://sridharkatakam.com/portfolio-genesis-featured-images-grid-revealing-title-excerpt-hover/

archive-portfolio.php

<?php
/**
 * Portfolio Archive
 * Author: Sridhar Katakam
 *
 */

//* Add portfolio body class to the head
add_filter( 'body_class', 'sk_add_portfolio_body_class' );
function sk_add_portfolio_body_class( $classes ) {
   $classes[] = 'beautiful-pro-portfolio';
   return $classes;
}

//* Enqueue Script
add_action( 'wp_enqueue_scripts', 'load_portfolio_script' );
function load_portfolio_script() {

	wp_enqueue_script( 'portfolio-archive', get_stylesheet_directory_uri() .'/js/portfolio-archive.js' , array( 'jquery' ), '1.0.0', true );

}

//* Force full width content
add_filter( 'genesis_pre_get_option_site_layout', '__genesis_return_full_width_content' );

/**
 * Display as Columns
 *
 */
function be_portfolio_post_class( $classes ) {
	
	global $wp_query;
	if( !$wp_query->is_main_query() ) 
		return $classes;
		
	$columns = 3;
	
	$column_classes = array( '', '', 'one-half', 'one-third', 'one-fourth', 'one-fifth', 'one-sixth' );
	$classes[] = $column_classes[$columns];
	if( 0 == $wp_query->current_post || 0 == $wp_query->current_post % $columns )
		$classes[] = 'first';
		
	return $classes;
}
add_filter( 'post_class', 'be_portfolio_post_class' );

//* Remove items from loop
remove_action( 'genesis_entry_header', 'genesis_post_info', 12 );
remove_action( 'genesis_entry_footer', 'genesis_entry_footer_markup_open', 5 );
remove_action( 'genesis_entry_footer', 'genesis_post_meta' );
remove_action( 'genesis_entry_footer', 'genesis_entry_footer_markup_close', 15 );

//* Do not show Featured image if set in Theme Settings > Content Archives
add_filter( 'genesis_pre_get_option_content_archive_thumbnail', '__return_false' );

add_action( 'genesis_entry_header', 'be_portfolio_image', 4 );
/**
 * Add Portfolio Image
 *
 */
function be_portfolio_image() {
	echo '<a href="' . get_permalink() . '">' . genesis_get_image( array( 'size' => 'portfolio-image' ) ). '</a>';
}

//* Force Excerpts
add_filter( 'genesis_pre_get_option_content_archive', 'sk_show_excerpts' );
function sk_show_excerpts() {
	return 'excerpts';
}

//* Modify the length of post excerpts
add_filter( 'excerpt_length', 'sp_excerpt_length' );
function sp_excerpt_length( $length ) {
	return 10; // pull first 10 words
}

//* Modify the Excerpt read more link
add_filter('excerpt_more', 'new_excerpt_more');
function new_excerpt_more($more) {
    return '... <a href="' . get_permalink() . '">More</a>';
}

//* Wrap .entry-header and .entry-content in a custom div - opening
add_action( 'genesis_entry_header', 'sk_opening_div', 4 );
function sk_opening_div() {
	echo '<div class="entry-content-wrap">';
}

//* Wrap .entry-header and .entry-content in a custom div - closing
add_action( 'genesis_entry_footer', 'sk_closing_div' );
function sk_closing_div() {
	echo '</div>';
}

//* Wrap all entries in a custom div - opening
add_action( 'genesis_before_loop', 'portfolio_entries_opening' );
function portfolio_entries_opening() {
	echo '<div class="portfolio-entries">';
}

//* Wrap all entries in a custom div - closing
add_action( 'genesis_after_loop', 'portfolio_entries_closing' );
function portfolio_entries_closing() {
	echo '</div>';
}

genesis();

functions.php

//* Add Archive Settings option to Portolio CPT
add_post_type_support( 'portfolio', 'genesis-cpt-archives-settings' );

//* Define custom image size for Portfolio images in Portfolio archive
add_image_size( 'portfolio-image', 691, 460, true );

/**
 * Portfolio Template for Taxonomies
 * 
 */
function be_portfolio_template( $template ) {
  if( is_tax( array( 'portfolio_category', 'portfolio_tag' ) ) )
	$template = get_query_template( 'archive-portfolio' );
  return $template;
}
add_filter( 'template_include', 'be_portfolio_template' );

add_action( 'pre_get_posts', 'be_change_portfolio_posts_per_page' );
/**
 * Change Posts Per Page for Portfolio Archive
 * 
 * @author Bill Erickson
 * @link http://www.billerickson.net/customize-the-wordpress-query/
 * @param object $query data
 *
 */
function be_change_portfolio_posts_per_page( $query ) {
	
	if( $query->is_main_query() && !is_admin() && is_post_type_archive( 'portfolio' ) ) {
		$query->set( 'posts_per_page', '10' );
	}

}

portfolio-archive.js

jQuery(function( $ ){

	// equal heights
	function equalHeights() {
		var $col = $('.portfolio-entries > *'),
			maxHeight = [],
			rows = [],
			rowTop = 0,
			rowIndex = 0;

		$col.each(function() {
			$el = $(this);
			$el.css('height', '');
			if ($el.offset().top > rowTop) {
				rowIndex++;
				rows[rowIndex] = [];
				rowTop = $el.offset().top;
				maxHeight[rowIndex] = 0;
			}
			if ($el.height() > maxHeight[rowIndex]) {
				maxHeight[rowIndex] = $el.height();
			}
			rows[rowIndex].push($el);
		});
		for (row = 1; row <= rowIndex; row++) {
				for (i = 0; i <= rows[row].length; i++) {
					$(rows[row][i]).height(maxHeight[row]);
				}
			}
	}
	// $(window).on('resize load', equalHeights);

	function setHeights() {
		$('.beautiful-pro-portfolio .entry').each(function() {
			var $imgh = $('.beautiful-pro-portfolio .entry img').height();
			$(this).css('min-height', $imgh);
		});
	}
	$(window).on('resize load', setHeights);

});

style.css

/* Portfolio Archive with Featured Images in a Grid revealing Title and Excerpt on Hover
---------------------------------------------------------------------------------------- */

.portfolio-entries {
	overflow: hidden;
	margin-bottom: 80px;
}

.portfolio-entries .entry {
	position: relative;
	background: #333;
	border-bottom: none;
	padding-bottom: 0;
	margin-bottom: 2.564102564102564%;
}

.portfolio-entries .entry-content-wrap {
	padding: 30px 30px 0;
}

.content .portfolio-entries .entry:last-of-type {
	margin: 0 0 2.564102564102564% 2.564102564102564%;
}
.content .portfolio-entries .entry.first:last-of-type {
	margin: 0 0 2.564102564102564% 0;
}

.portfolio-entries .entry-title {
	font-size: 20px;
	margin-bottom: 10px;
}

.portfolio-entries .entry a {
	color: #b8e3b4;
}

.portfolio-entries .entry a:hover {
	color: #cff0cc;
}

.portfolio-entries .entry-content p {
	margin-bottom: 0;
	color: #fff;
	font-size: 15px;
}

.portfolio-entries .entry img {
	display: block;
	left: 0;
	position: absolute;
	-webkit-transition:  all .2s linear;
	-moz-transition:  all .2s linear;
	-o-transition:  all .2s linear;
	transition:  all .2s linear;
}

.portfolio-entries .entry img:hover {
	-ms-filter: "progid:DXImageTransform.Microsoft.Alpha(Opacity=10)";
	filter: alpha(opacity=10);
	-moz-opacity: 0.1;
	-khtml-opacity: 0.1;
	opacity: 0.1;
}

@media only screen and (max-width: 1024px) {

	.portfolio-entries .entry img {
		position: static;
	}

	.portfolio-entries .entry-content-wrap {
		padding: 30px;
	}

	.portfolio-entries .entry img:hover {
		-ms-filter: "progid:DXImageTransform.Microsoft.Alpha(Opacity=100)";
		filter: alpha(opacity=1);
		-moz-opacity: 1;
		-khtml-opacity: 1;
		opacity: 1;
	}

	.portfolio-entries .entry-title {
		margin-bottom: 20px;
	}

}

@media only screen and (max-width: 768px) {

	.portfolio-entries .entry {
		margin-bottom: 5%;
	}

}