Photography tips

If you read the last post, you know a little about cropping, resizing and compressing your photos for use on a computer or website. well, now I am going to go thru a few things to get the best possible print from your digital files.

You are going to hate me again, because we have to do some basic maths to understand how much we can crop a photo and how big it needs to be if it is going to be printed. we will get to this in a minute or so. First, I will assume that we are going to prepare our pictures and take them to the local photo lab to do the printing for us.

Standard print sizes are measured in inches. The most common sizes are 6x4, 5x7, 6x8, 8x10, 8x12. Of course, there are larger sizes as well but in our discussion, I am only going to look at the first 3 of these sizes - it will become clear why by the time you get to the end of this.

The best quality prints will come from photos that are a certain size. The  minimum size needed to get the best quality is 300dpi or Dots Per Inch. You can use less DPI but the quality of the prints goes down very rapidly with any reduction, so you should avoid going smaller than 300DPI at all costs.

Here comes the maths! now if we want to  print a 6x4 inch photo, we want a photo that is 6x300 (1800pixels) by 4x300 (1200pixels). You can probably already guess that if you have a 2Megapixel camera, it only takes pictures around 1200x1600 - we can get away with the picture being just this bit smaller.

You will have noted that the shape of a 6x4 is different to the shape of your photos. Most Digital Cameras  have a 4/3 ratio, where a standard print has a 6/4 or 3/2 size. Now if we simply use our 4/3 photo and take it to get 3/2 prints there is going to be some cropping of your photo - the lab will trim a little bit off the top and bottom to get the 3/2 size -and you have no control over what they chop off!

So, now we want to get our photo printed and cropped exactly how we want it to look. If you already downloaded and installed Picassa, then the maths and the cropping of photos for various sizes is simple! It has a nice tool so you can choose the print size, and select the print area. Go in and select a photo and under basic fixes, there is a crop photo option. Choose the 10x15 (yes, they have gone metric on us) and select the biggest area you can of your original photo. You will notice that there is a fair bit that you cannot actually select.

If you had taken your 4/3 picture to the lab for printing, they would simply crop the same amount off the top and bottom. This might be ok, but in some cases it isn't. That is why we want to do our own editing and by doing so, we get to choose the bits we crop and the bit we get printed.

Now we have chosen the crop area, you might want to do some other "fine tuning" of the photo using the other options. I won't go over the options again - I already covered that in my last post.

We have done our edit, selected our print area and we are ready to export our photo ready to take it to the lab for printing. Here is where we do somethething a bit different than when we saved for computer use. We want the best quality picture we can get, so when we export our new picture and save it ready for printing you want to ensure that you do not resize it! (we already did that) Also, we want the best quality, so we select 95% JPEG compression and save our file. You might ask why we dont save it at 100% and the answer is that we gain nothing by saving it higher than 95%.

If you wanted to do a 5x7 print, you would follow a similar process and just select the 13x18 size to crop the picture. Now, if we want a 6x8 picture, we don't need to crop as it is already in the right shape.  I hope you get the idea about cropping a picture for various print sizes from here and can work out any others sizes and ratio's for larger prints.

At this stage, we will have our new file, all ready for print. Well, not quite! we still have 1 more thing to do to make sure we will get a good quality print and that is to check that we actually have enough pixels for our desired size print. You should be able to look at the photo properties of the photo we exported and all we need to do is make sure that the size is at least 1800 pixels by 1200 pixels for a 6x4 inch photo.  If it is bigger then that is fine, but if it is smaller, the print will probably be lacking a little bit.

Ok, 300dpi is our target, as that is the native resolution of the photo printers in most photo labs for prints up to about 9x13inches. It will probably be acceptable as low as 250 dpi ( that is 250x6 by 250x4 or 1500pixels by 1000pixels).  If you go lower than 250DPI then accept the fact that your picture will probably look better on the screen than printed out.

As prints of this size are quite cheap - normally less than $0.50 each, You can of course prepare a few photos at different DPI and get them printed out and see for yourself.

Well, we now have our pictures ready to take to get printed, so once again, burn the exported photos to a CD for backup purposes - we don't want to have to edit them again if we want more prints do we!

Most photo labs will accept your images on a CD or memory card. It is normally easier to copy the prepared pictures back onto a memory card to take them to get printed. So, what are you waiting for? go and get a couple of prints and see how good they are knowing that you had total control over what is being printed!

If you got thru all of this, you will probably have at least 3 copies of your pictures on CD for safe keeping. You will have the original, a copy you prepared for displaying on a computer screen and your copy that you will use to get your prints done from.