How to randomize large datasets?

Actually there is one more way, you can add the images as a choice in multiple choice question and in Advance randomization, display randomly 3 choices, make sure to select evenly present checkbox and add the below code in JS, it will select the random 3 images.
Create the 3 embedded data variables in the survey flow above the question, in the below code these are firstPicture, secondPicture and thirdPicture
Qualtrics.SurveyEngine.addOnload(function()
{
/*Place your JavaScript here to run when the page loads*/
jQuery('.QuestionOuter').css('display','none')
});

Qualtrics.SurveyEngine.addOnReady(function()
{
/*Place your JavaScript here to run when the page is fully displayed*/

jQuery('input[type="checkbox"]').prop('checked',true)
jQuery('#NextButton').click();
});

Qualtrics.SurveyEngine.addOnUnload(function()
{
/*Place your JavaScript here to run when the page is unloaded*/

});

Qualtrics.SurveyEngine.addOnPageSubmit(function(type)
{
if(type == "next")
{
var qid= this.questionId
var firstimg = jQuery.trim(jQuery('#'+qid).find('.Selection').eq(0).text())
Qualtrics.SurveyEngine.setEmbeddedData("firstPicture",firstimg)

var secondimg = jQuery.trim(jQuery('#'+qid).find('.Selection').eq(1).text())
Qualtrics.SurveyEngine.setEmbeddedData("secondPicture",secondimg)

var thirdimg = jQuery.trim(jQuery('#'+qid).find('.Selection').eq(2).text())
Qualtrics.SurveyEngine.setEmbeddedData("thirdPicture",thirdimg)

}
});