Use an assortment of Photoshop’s automated tools to easily produce an interlocking photo mosaic
Use the magic wand to select the magenta background and delete it. The whole reason bright magenta was used for the matting was to make for easy selections without having to worry about accidentally grabbing portions of the image tiles. Go to Layer>Matting>Defringe to remove any residual edge pixels.
Reopen your project file, drag and drop the mosaic layers onto the file and position to fit. You may need to scale the tiles slightly to get the edges to line up with precision.
Make a copy of the Blur layer and move it to the top of the layer stack. Change the blending mode to Hard Light. This will colourize the tiles with the hues needed to form the larger image.
Make a copy of the tile layer and flip it horizontally to avoid visual repetition. Reposition this new layer to interlock with the original tiles. Continue duplicating, transforming, and repositioning tile layers until the canvas is covered. To help keep things organized, group all of the tile layer together.
Now that the tile work is complete, it’s time to bring back some of the important detail of the original image that was lost in the mosaic process. Create a copy of the background photo layer, move it to the top of the stack and set the blending mode to overlay.
The details are overpowering the mosaics now, so add a layer mask by using the New Layer Mask icon at the foot of the Layers Panel. With the mask targeted, go to Edit>Fill add layer mask, fill 50% grey. This effectively lowers the layer visibility to 50%.
With the layer mask still targeted, you can bring out details in the windows and the centre of the sails by using the dodge tool set to 30% exposure. Conversely use the Burn tool at the same setting to hide details that are visually intrusive such as the brick siding.