Constructing Mosaics in Photoshop
Quite often I find that software for constructing mosaics doesn't always perform quite as the user thought. The Photoshop panorama maker often works well, but with large mosaics the blending sometimes goes a little awry. That is why I have made this tutorial on constructing mosaics in Photoshop. I hope it isn't too difficult to follow!
- Step 1
- Load the components of your mosaic into one large image (big enough to fit them all in with space to spare)
- Align them to the best of your ability - I find that if you change the opacity to around 50% you can get a good feel of where the top image should be. Quite often Photoshop will lock the images into place for you - see the image below!
- Step 2
- You might find that RegiStax (or whichever stacking program you use) puts little white borders around each of your images. You need to remove these.
- Select the borders and (after ensuring that you have the correct layer selected) hit delete
- Step 3
- This is possibly the most frustrating step, especially if you have a large mosiac
- You must adjust the levels of each image so it appears to match the images surrounding it to the best of your ability
- You will probably find that an image will match in some places, but not in others (see image below ) - don't worry about this too much. Get it as close as you can.
- Here is the zoomed out mosaic - you can see what doesn't match!
- Step 4
- Now for the 'fun' part - hiding the seams
- Find a seam which is clearly visible (see below). It wil be between two images - one will be above the other. Select the top one.
- Create a mask for this layer. Keep this mask selected by clicking it, but make sure you can see what you are doing (see below)
- Using whichever tool you like, select an area around the seam - the bigger the better, but make sure you only select the area of overlap between the two images otherwise you will end up with holes in your image
- Select the gradient tool, and make sure your two selected colours are black and white
- Drag from one side to the other (perpendicular to the seam) - this is where the art really comes in. Depending on the 'severity' of the join, you will find that you will get the best results if you start and stop the gradient in different places etc.
- Note! If you find that you get a big hole, it might be because you are drawing the gradient the wrong way, or you are using the wrong type of gradient (you need the linear one)
- ...and with the gradient applied, the seam disappears!
- To give you an idea of what the masks look like, the image below shows all the masks in that area overlayed onto the image. You will notice a funny 'blob' at the right-angle on the lowest mask - when you get seams that are at right angles, you can fade them away by using the paintbrush tool and effectively painting them out.