There may not be a quick and simple way to "let" Photoshop do htis assignment.
Covering a pattern while keeping the shadows and lines of the dress are not exclusive. Both are essentially patterns. So if you cover the pattern, you're covering the wrinkles and so forth. Also, the quality of the photo and business of the pattern makes it difficult to follow the bends and shadows. This is a quick job so not high quality. :mrgreen: It is also probably more involved than you want to get.
It's not a good selection nor a careful painting, but I don't know how else you might do this. And depending on your purpose, it may not look realistic. I think it could if you devoted time to it, but if you don't have some painting expertise it will be difficult. That said, here is my solution:
The bottom layer is the original. The second is a selection of the dress. Ignore the 3rd layer; I only did this layer because I was playing around with the opacity of the color. Next layer is the color desired, clipped to the dress selection. The top layer is set to soft light blending mode. I used a soft low opacity brush also set to soft light to create the shadows. When you do this, first ctl/cmd click on the dress selection thumbnail. Now you can paint freely around the edges yet stay confined to the dress. You could do another layer to add highlights and give the dress more dimension. Set that one either to screen, overlay or soft light. I'd play with it more but yawn . . . bedtime.
Problem with this is Twelvebitstyle never got back to us. Those examples look very good, but how were they done? Mine was a sloppy quick example, but still I couldn't get anything to work without painting in the shadows and highlights myself. You'd think there might be a better way, but again, how can Photoshop determine the difference between shadow-dark pixels vs. pattern-dark pixels. I don't think displacements maps would work because of the solid color of a fill. Maybe with painted shadows, you could get those to be more realistic with displace filter. I'll have to try it though.
I did not make a great selection on the model and I am not really that good with the painting. I just don't know of a better way to get this result. Even the stores which change color on a shirt or dress, etc. already have the basic outfit and only have to change hues. I think. Patterns are a different shot. Again, I think. Who wants to contact their art depts?
So, this result is not the most realistic. But the best I could do given the time; or maybe just the best I can do. If you only want to do this to one object, I'd try to find an easier way, unless you consider it a must. I will try to give a brief description of what I did.
Mostly it is painting, smudge, more painting, a little soft eraser, gaussian blur and levels adjustment.
If it is possible, the time and money spent (aka, wasted) on trying to achieve this in PS using the above methods would, IMHO, be much better spent on having the photographer shoot a few more shots with different dresses with solid colors. With these in hand, one can easily change the (solid) color in a much more realistic and cost-effective way than any of the above PS-based methods.
There is an old saying that if one has a hammer in one's hand, everything, including screws, will look like nails. I think the request to use PS for this task is an excellent example of using a hammer for a task best done with another tool, photography, or photography plus some minor PS work.
OTOH, if I had a gun to my head, and there was absolutely no way to get a few more photos taken of the same model wearing a solid, so I had no choice but to use PS, I would find a good quality photo of a model with a similar build, lit similarly, but wearing a solid color dress. I would then copy the dress from this picture, and then warp, transform, liquify, and do whatever else was necessary to get it to lay well over the old photo and blend with it in an appropriate manner.
Even using this method, if your time (ie, in PS) to do this is costing someone $$$, my guess is that in the future whomever is paying for the work will probably consider more carefully the option of paying a photographer take a few more shots of the original model.