You can achieve that by customizing a bit in blog item : templatesja_argohtmlcom_contentcategoryblog_item.php
<?php if (isset($images->image_intro) and !empty($images->image_intro)) : ?>
<?php $imgfloat = (empty($images->float_intro)) ? $params->get('float_intro') : $images->float_intro; ?>
<img
<?php if ($images->image_intro_caption):
echo 'class="caption"'.' title="' .htmlspecialchars($images->image_intro_caption) .'"';
endif; ?>
src="<?php echo htmlspecialchars($images->image_intro); ?>" alt="<?php echo htmlspecialchars($images->image_intro_alt); ?>"/>
<?php endif; ?>
replace it with:
<?php if (isset($images->image_intro) and !empty($images->image_intro)) : ?>
<?php $imgfloat = (empty($images->float_intro)) ? $params->get('float_intro') : $images->float_intro; ?>
<a href="<?php echo JRoute::_(ContentHelperRoute::getArticleRoute($this->item->slug, $this->item->catid)); ?>"><img
<?php if ($images->image_intro_caption):
echo 'class="caption"'.' title="' .htmlspecialchars($images->image_intro_caption) .'"';
endif; ?>
src="<?php echo htmlspecialchars($images->image_intro); ?>" alt="<?php echo htmlspecialchars($images->image_intro_alt); ?>"/></a>
<?php endif; ?>
Hope this helps.