I consider to generate and place really HUGE large image preview pages for every stock image available on my personal portfolio website, in the way shown on this sample localhost screenshot:
http://www.jareso.com/temp/jareso_com_screenshot_large_preview_photo_268_sample.jpg

The main reason why I consider something like that are naturally possible SEO benefits.

Theoretically, large *.jpg images should rank better in search engine result pages (SERP) than images that are smaller in size.
You can see it when you perform image searches in search engine like Google. Higher resolution images are usually positioned higher whereas lower resolution images are buried down in SERP.

For now, *.jpg image previews on my personal portfolio website are quite small, such as here for example, it is just 400 x 547 pixels, that is too small:
http://www.jareso.com/photo/268/entrance-to-the-strecno-castle-slovakia/

That small preview resolution is not sufficient enough for proper ranking in SERP in the way how I imagine it should be. I mean, the thing that bothers me the most is that stock agencies over-rank my personal portfolio website in image SERPs, and all of that with help of my own images I uploaded to them.

I strictly believe that author's personal portfolio website should always rank better than any other source where his/her images are available online for sale, how I noted it here at MSG some time ago:
http://www.microstockgroup.com/selling-direct/author's-personal-website-should-always-rank-better-than-agencies!-shouldn't-it/msg328165/

No, I am not that much naive to think that � out of nowhere � suddenly my little personal portfolio website will rank better in SERP than those big stock agencies.
But I want to at least try it!
(I am very stubborn person when it comes to these things.)

Let's take a look at that castle image I have given as an example here. On my personal portfolio website that *.jpg image has just 400 x 547 pixels in size. So naturally that when it comes to searches in SERP it is over-ranked with the same image, but in much higher resolution available. Stock agencies do it in the way that they offer preview image, approx. 500 pix x 500 pix on their stock image preview pages, but than they usually link from that image to much higher resolution image, which they call "compositional preview", "image zoom", or whatever. Those "image zooms" are usually available in much higher resolutions than simple image previews are. Such as they are over 1000 pixels on each side.
So agencies do more or less exactly what Google image guidelines suggests.
https://support.google.com/webmasters/answer/114016?hl=en

It suggests that, when there is smaller preview image available on webmaster's website, than - if possible � that smaller image should link much higher size of-the-same-image if such image is available.

Google tries to serve user who is searching for images in Google Images, in the best way, so naturally it picks one at a time image of that kind, to be shown in SERP. So only one image (only one image of the same image) is chosen to be shown, and most of the time it seems to be the highest resolution one.

OK than, if it is only size what does matter.

Why not to put HUGE *.jpg preview images on personal portfolio website to possibly over-rank any other source where that particular image can be available online?!
According to Google guidelines and even probably according to reality Google should choose that image � the biggest one - to be shown in image SERP.

I mean, agencies do have big "compositional preview zooms" on their image preview pages, but those "compositional preview zooms" are still usually much smaller than original resolution of image.
For example, highest resolution "compositional preview zoom" image of my castle image (given here as an example) is available online at DepositPhotos. It is 768 x 1024 pixels in dimensions, and as expected that DepositPhotos "compositional preview zoom" is usually chosen by Google to represent (various image searches for) that particular image, and thus that DepositPhotos "compositional preview zoom" *.jpg image ranks usually the best in Google image SERP (for that particular image).

So, OK. But 768 x 1024 pixels is not that big!

What if I generate "compositional preview zoom" for my personal portfolio website, that will be much bigger in dimensions than any other "compositional preview zoom" available online at stock agencies, (or available online anywhere else)?!

I mean, from this large image preview page, where image is only 400 x 547 pixels in size:
http://www.jareso.com/photo/268/entrance-to-the-strecno-castle-slovakia/

I will link to my "compositional preview zoom" page, such as this one on the screenshot:
http://www.jareso.com/temp/jareso_com_screenshot_large_preview_photo_268_sample.jpg

Where that particular image will be available for example in 2449x3265 pixels, which is original dimension of that image actually.

Now I ask, what will (or should) happen?!

According to Google guidelines, my "compositional preview zoom" *.jpg preview image that will be avaleable on my personal portfolio website should be chosen by Google as representative image of that kind, because it will be MUCH bigger in dimension, than any other (same) image available online anywhere else.

So *** theoretically *** it should over-rank any of the stock agencies in image SERP, shouldn�t it?
(*) That is what I want to try. That's why I consider this - to try it, and to see what will happen, and of course to rank in the best possible way with my personal portfolio website.

What do you think about that.
Share what are your opinions, or whatever.

I will probably try it anyway, just to see it myself, because I like SEO experimenting very much! 

The very short answer is that I have no idea what will happen, but...

There appears to be some sort of arms race with the agencies and their preview images - 123rf is the current leader in "lying" about the image preview size, telling Google it's three times the size it actually is and thus getting their images ranked higher in Google searches in many cases. Although my blog post was about improving search results in other ways, you can see some examples of agency images vs. my own site's images in search results in this post:

http://www.digitalbristles.com/getting-our-names-with-our-images-in-the-search-wilderness/

The other thought would be that you want the buyer/visitor experience to be a good one and part of that would be page load times that are reasonable. Doing something with your preview images that got you a high rank but that made visiting your page slow and not appealing wouldn't seem to be a good idea. My original images are typically 5616 x 3744 and those files can get quite large (from the perspective of displaying on a web page).

If you do experiment, it'd be nice to know what you find out

FYI

http://www.seo-theory.com/2013/04/10/how-the-google-panda-algorithm-works/

Heck the Big Bang Theory is easier to figure out! Than move on to warp drive...

Thanks everyone for your opinions! I will probably try it soon, and will watch the results (if any).
Naturally effect of it will not happen overnight, I guess it will take weeks, or months for positive changes to be reflected in SERP (if ever).
But, of course if it will work for me, I will share outcome from this tryout.