Superimposing 2 images of different scale and rotation

[HaimSh]

Hi All,

I am a researcher of ancient coins. Every ancient coin is hand made, and like snowflakes, no two are alike. However, much can be learned by tracing the minting process of these coins through an examination of the dies used to make them. So, I have to compare different coins to see whether they were minted using the same dies.

In order to do this I have to align two coin images on a Photoshop grid using two identifiable points that are visible on each coin. However, since I have collected these images from various coin collection sources, they are usually not of the same scale or rotation. So up until now, I have been putting two layers, each with one coin, on a white background with the grid showing, and slowing pulling the handles of the "transform" to get them aligned with each other and sized the same - exactly superimposed. Then I use the opacity function to check whether all the coin features line up, and they were made by the same die. However, this is very tedious! It takes dozens of nudges, pulls and rotations to get the two layers lined up exactly one atop the other. But, I have hundreds of coins to examine, and I have to find a better way!

My question is: Is there a way to simply "anchor" one point of the layer at a particular point on the background, and then "stretch" the other point to another point on the background while preserving the aspect ration of the layer? That way I can superimpose the two images in a snap!

I am attaching a Photoshop file of one such superimposition so that you can see what I am facing.

Many Thanks for any solutions or suggestions.

Haim

[c.pfaffenbichler · Accepted solution]

First off: Smart Objects, Smart Objects, Smart Objects! 

• Set the top SO to 50% opacits and align one point 

• cmd-T

• set the Reference Point by click-dragging 

• press the alt-key to scale and rotate the SO from that point 

Or is that what you are doing now, anyway? 

[HaimSh]

Thank you very much for this information!! I didn't even know about Smart Objects!

This will save me months of work!!!

I will read a tutorial or two on this and figure out how to use it.

Thanks again!

[c.pfaffenbichler]

Even for non-Smart Objects setting the Reference Point to the one point of clear »congruence« can be quite useful when transforming a Layer. 

But SOs can be repeatedly transformed without accumulating resampling damage, so they may be worth a try. But they will increase the filesize … 

[HaimSh]

This is GREAT!! It reduced a ton of workload!!!! This might have seemed a no-brainer to you, but I am not a graphics person but an archaeologist, so please forgive the ignorance. I am indebted!

[c.pfaffenbichler]

No sweat, this Forum is open to anyone with Photoshop-questions, no matter their level of experience. 

[HaimSh]

Hi again c.pfaffenbichler, Following up on this subject ... I have been moving forward with the ancient coin die superimposition (many thanks for showing me how!), and I find that I am accumulating little red dots (which I have added to the layers/SO's to assist in lining up the images), which I need to remove somehow. I would like to make a composite image of the die from the best sections of each coin, and these dots would messy the result. How can I remove them without "undo"ing all my work and ruining the superimposition? No need to explain step by step. If you just point me to the proper tool or action, I will do a tutorial on it. I am attaching an example of superimposed coin images.

Thanks for your help!

Haim

[EuanWilliamson]

Perhaps I can jump in 😉

Place the dots for a coin sample in a layer IN the smart object. Remove or make that layer invisible

when you need to make the final composition.

This way, the alignment dots move with the SO coin image while aligning  🙂

[HaimSh]

That's a very good idea!! I'll try that right away! Thanks Euan!!!

[EuanWilliamson · Accepted solution]

May I just add that having had to do something similar although not with coins,

You can combine the method @c.pfaffenbichler has outlined with

set the upper layer coin to difference mode.

Where the coins and dies are the same, the composit image will be black.

Where there are differences, they will show up. I've simulated this by duplicating one

of your coins and slightly offsetting the layers.

 

[HaimSh]

Thanks Euan very much for this suggestion. That works nicely!

[EuanWilliamson]

You are most welcome.

I forgot to say, obviously you can use the opacity value to help see the alignment.

[War Unicorn]

I wish I could mark both c.pffaf and Euan's answers as correct because they're both great answers.  : /

[EuanWilliamson]

That's very kind.

(ps I think you can)

[War Unicorn]

You can, kind of, sort of; the first marked correct answer is highlighted at the top, while any other answer marked correct will simply have a green checkmark and "correct answer" next to it.