“From your site and the other information I've found on the net, I think we should scan our photo collections in TIFF, at 600 dpi, using your naming convention / workflow. You don't cover TIFF versus other formats in your articles, but I see you are using that format and there seems to be general acceptance that it is the best format for archiving.
What do you think of the PNG format? “
Wellington, New Zealand
Peter, that is a great question. And you're right, up until now I have not covered what I feel is the best file format(s) to save scanned photos with. But, as you astutely noticed, I did sort of allude to my personal choice in a couple of my posts. Especially in some of my images I used in my 3-part “naming convention” series you brought up called What Everyone Ought to Know When Naming Your Scanned Photos.
I think your question actually deserves a slightly more complex answer than I could normally get away with. Had you simply asked, “Which do you prefer for scanning photos, the TIFF or PNG format?”, I would feel comfortable quickly answering you that in my humble opinion, the TIFF format is by far more superior for the purpose of scanning photos. But, since you brought up your interest in “archiving” your photographs, I want to make sure I elaborate a bit more to explain why our personal goals of scanning need to be considered when making the final decision which file format to save our master image files.
PNG files (Portable Network Graphic) were invented to replace the GIF format (Graphics Interchange Format) that was quite popular at the time for images on the internet. They really weren't intended to be used for professional-quality photos. Currently on the internet, you will primarily see JPEG and PNG files followed by the lingering GIFS.
- can only be saved compressed (“lossless” – reduces file size)
- can hold an alpha channel
I use PNG files here on the SYEL website a good portion of the time because they have small files sizes and I love being able to use the alpha channel. This is a fancy way of describing a “compositing” process where the image can have a transparent background so you can lay it on top of another image and use it as the first image's background. It's very cool! And in case you're wondering, no, JPEG files don't do alpha channels.
TIFF files (Tagged Image File Format) on the other hand:
- can be opened with almost every image program (it's an extremely common format)
- can be saved compressed or uncompressed
- can store “layers” within (great for use with Adobe's high-end Photoshop for example)
- can hold all color, color depths and color groups (like RGB and CMYK)
- can save 16-bits per channel scans (your 48-bit scanner setting)
- can store IPTC metadata (captions etc.)
In my opinion, one of the biggest reasons not to use the PNG format for photo scanning – and more importantly archiving photos – is because it's a form of compression. It's a form of compression called “lossless,” which as you might already know, means that your photo will be saved without having any of the data (details) of your photo “tossed out.” However, the image is still undergoing a very complex process using a mathematical algorithm to compress the file so that it will take up less space on your hard drive.
So let me explain why this should be important to you.
Do You Have Basic or Advanced Goals?
To keep it simple, if you are about to scan your entire photo collection, you are probably going to fall into one of the following two categories. First, you might be the type of person that just wants to get a good-looking scan of all of your photographs as quickly and easily as possible. If you feel this might describe your needs, I like to say that you are someone with basic goals.
Now don't take that the wrong way. I don't mean to say basic in a negative way. The fact that you are even wanting to scan your photos already says a lot about how much you care about your collection.
When Peter brought up archiving, to me it implies he's stepping into the shoes of someone in the second category. Someone with advanced goals is a person I feel is invested from the very beginning to make the decisions that will insure everything they do throughout the workflow of scanning, correcting and managing their photos, will preserve every last bit of image quality (detail) they reasonably can. Those with advanced goals also are willing to sacrifice more of their time and possibly money – which in many cases is not that much more – for the ability to create and store these higher quality images.
Let me quickly add, having advanced goals is by no means exclusive to those seeking the level of perfection a lifelong professional in the graphic arts field would produce. You don't need to be an expert to have advanced goals. We all have our own personal limitations and expectations for our collection.
What I Really Think of Compression
I believe in my heart, that if you are going to really go at archiving your entire photo collection – I mean really give it your all – you should scan them with adequately high DPI settings, save them “raw” without lots of filters and computations altering the outcome of the master image during the scan, and save and archive them uncompressed. I know this might be asking a lot of you, but the sacrifice has its rewards.
If you are considering compressing your images, to save hard drive space or ease the processing load on your current computer, just know you are taking steps toward the side of people with more basic goals. I just want to make sure you understand this.
Many may disagree with me, but I consider compression, even the lossless kind, to be an act of compromise to the overall integrity of your collection.
The hugely popular JPEG file format (Joint Photographic Experts Group) also uses compression. And it's even more severe because it's a form of lossy compression. Lossy means your file size will typically be even smaller than that of lossless, but at the cost of reduced image quality. And once the detail is gone – it's gone. If you're lucky, your eye won't be able to see what's now missing.
Even worse, every time you re-save a JPEG as a JPEG, you are “tossing out” even more information in addition to the information you got rid of before. It's compounding detail loss!
Non-destructive image managers will however automatically protect you from this additional image loss when you make edits to your photos inside. This is why I highly recommend everyone start using one. (Check out Use 1 of These 4 Photo Managers If You Care About Your Photo Collection)
Additionally, and I know this is really more theoretical, the second you bring to the table the option of compressing your masters, you introduce a greater possibility for file corruption. You're putting more trust in that mathematical formula to “destruct” your photo now and “reconstruct” it later than you may want to give it. Some formats have so many variant types of compression, who is to say that “shareware” graphics program you found one day off the internet to compress your images will be around 20 years from now? What if their proprietary scheme doesn't open correctly in the version of Photoshop you buy in the future? Then what are you going to do?
The Best Format to Save Your Scanned Photos
You are the safest saving your master images in the most common, nonproprietary format that you possible can. And if you are swinging towards the advanced side of goals for your collection, you want to save your files uncompressed. Yes, uncompressed files are huge, but so are the capacities of average priced hard drives on store shelves today.
The two most common formats that I feel safe recommending to you are JPEG (high-quality setting) for those with basic goals and TIFF (uncompressed) for those with advanced goals. It's also the two formats all of the major scanning services feel safe saving your precious memories in as well.
Wow! And I bet Peter thought this would be a simple answer to a simple question! Leave it to me – just get me all wound up and it all comes out!
I hope that all made sense. If I left out anything you are wondering about, just ask me in the comments below. I will be glad to answer them for you!
Thanks for that question Peter from over there in beautiful Wellington, New Zealand! And if you have a question of your own you would like me to cover in an article like this one, ask away using my contact form. Cheers!