Alamy used to require images in 8 bit mode with an uncompressed size of 48mb, with a colour space set to Adobe RGB. Now Alamy do not insist on the files being upscaled as this often caused confusion. This guide is still handy for up-scaling images for printing and if you still want to upscale your images before uploading them to Alamy.
so here is a brief explanation of how to do this in Photoshop.
A lot of people mistake the 48mb file size that Alamy specifies as actual file size, but it’s referring to the uncompressed size. In the bottom left had corner of Photoshop there is a set of figures. The right hand figure is the one you want to look at, this is the uncompressed size which needs to be 48mb or greater.
Having loaded your image and assuming its ready to be up scaled (often referred to as interpolated), make sure the image is flattened (i.e. just 1 layer). In the menu at the top select the image tab and select image size. (ALT+CTRL+I) If my image is not cropped I tend to set the widest side to 5100 pixels. This normally gives me a file size of 49.6mb (if you are working with a 16bit image this would be 99.2mb at this stage.) Set the resolution to 300 pixels/inch, and then making sure resample image is ticked, set the drop down to bicubic smoother (best for enlargements).
Once that is completed it is worth now zooming to 100% and checking the entire image for excess artifacting (jagged edges) or blemishes, as this would cause the image to be rejected.
So we are good to go, there are no jagged edges or blemishes. The next step is to make sure our image is 8bits/channel. To do this go to the top menu, select image then mode and tick 8bits/channel. If you were working with a 16bit image your image should now half in size. Obviously if it’s already set to 8bit no change would occur.
The last step is then to make sure we are using the right colour space. If your work flow is totally using Adobe RGB you shouldn’t need to change but it’s worth checking anyway.
To do this go to the top menu and select edit, convert to profile. If you can’t see this first go to edit, show all menu items. If your source space is Adobe RGB you can hit cancel and skip this stage. If it isn’t, change the destination space to Adobe RGB. In the intent section select perceptual and click OK.
Now we are done. Save your image as jpg at maximum quality and it’s ready to go. 
Alamy’s current quality control policy is to reject a whole batch of images if one fails, so I recommend uploading small sets the first few times of 1-10 images. This way if you do get rejected you haven’t wasted hours and hours editing and uploading hundreds of files.
I hope this guide was of use to you. Best of luck with your sales!
Dave
© 2012 Dave Gibbeson. All rights reserved
