Photoshop: JPEG -> TIFF -> JPEG Again

[michael_maxwell1]

Ok, I tried a little experiment. I imported JPEG images from my D70,

loaded them in photoshop and immediately converted them to TIFF. I

did some work on the image - basically a little dodge/burn,

sharpening, etc... I then tried to save the image out as a JPEG

(Using photoshop's "Save for Web..." option) and the end result was

horrendous. Colours were all out of whack, image was washed out, etc...

 

Now, being rather new to digital photography (I am still a film

purist, I guess), I know I must have made some simple and stupid

mistake, but I'm not sure what. Can anyone suggest how to do this

correctly?

 

Note: the reason I wanted to convert the image to TIFF in the first

place was to prevent corruption of the original JPEG when doing edits

- as I understand, JPEGs lose detail each time they're saved due to

recompression.

 

Any help would be much appreciated.

 

Thanks.

[beauh44]

Hi Michael, Try converting your image to sRGB before using Save for Web. Regarding the jpeg image deterioration: It's true that jpeg is a lossy format but I doubt there's anyone in the world who could tell the difference between a jpeg saved once versus a jpeg saved two, three or four times. I doubt it's buying you anything converting to tiff first; If you just need a jpeg file, you can use File>Save As and then specify jpeg as the format. If you need to post images on the web, I would just work from a copy of the original, resize the file(s), convert to sRGB, then use Save for Web. Good luck!

[frank_dzambic]

The only way you'll prevent corruption of the original JPEG is if you save the file you worked on under a different name than the original.

 

Converting to TIFF then back to JPEG is simply a waste of time. You're better off shooting in TIFF in the first place. (Or in RAW and converting straight to TIFF with no JPG in between).

 

All you've done from what you've described is what you were trying to avoid anyway. (Unless you saved the file you worked on under a different name than the original JPG). You opened a JPG, you worked on it, and then you saved it, with the additional unnecessary step of converting to TIF and back in between.

[andrewpgrant]

As I understand it, TIFF is also a format which compresses an image, so everytime you convert JPEG to TIFF and back again you are losing data.

 

You'd be better off taking the image in JPEG (D70's don't allow you to take photos in TIFF, if I remember correctly) and then, once in Photoshop, saving your image as a Photoshop document. This way you can continue to manipulate your image file through as many versions as you like without losing any picture quality, and then reserve the conversion to TIFF/JPEG for when you actually need a purpose-oriented image output.

[emre]

Your understanding is flawed. There are two types of audio/video compression: lossy, and lossless. TIFF falls in the latter category, and can therefore be resaved without incurring degradation.

[butch_welch]

Once the original jpg is open on your screen it is no longer

compressed. No matter how many times you save it while

working on it you will not be adding any additional compression

artifacts - as long as you continue to keep the image open and

work on it. The only additional compression artifacting will occur

the final time you save the file and close it. Each time you save

the open file you are "replacing" the original jpg with a new one,

still only equal to 2 compressions. If you closed and reopened

the file each time you saved it would add an extra compression

cycle. With large files, 2 jpg compressions are unlikely to be

obvious. On a small web sized file you would most definitely see

deterioration each time you saved and reopened.

[andrewpgrant]

>"TIFF falls in the latter category, and can therefore be resaved without incurring degradation"

 

TIFF compression is only "lossless" with small amounts of compression. If you are working with an uncompressed TIFF, then you are probably working with a huge, unwieldy file, which is not always a pleasant way to edit images unless you have some serious hardware at your disposal (not all of us have this luxury).

So yes, what I said was literally incorrect (sorry). You could resave your file as an uncompressed TIFF and not lose anything. But in terms of practical editing...

 

PSD is very similar to TIFF (and, sadly, can also be huge and wieldy at times), however you have the benefits of it being better integrated into the Photoshop software and you can keep your editing layers when you save. It's the lesser of two 'large-file-size' evils, IMHO.

[emre]

I am sorry to say it, but you are still wrong. TIFF has two common variants: uncompressed, and lossless compressed. In any case, you can resave without any degeneration. Note that there is no possibility of compressing a "small amount" as there is with JPEG.

 

Maybe you are thinking of layered files becoming flattened once you save to anything but PSD?

[andrewpgrant]

>"Maybe you are thinking of layered files becoming flattened once you save to anything but PSD"

 

No, although that did occur to me as another 'loss of information' in a different sense.

 

>"Note that there is no possibility of compressing a "small amount" as there is with JPEG"

 

No? Okay, fair enough.

 

Perhaps I have misunderstood the finer points of what I've 'learned' about file formats and should go back and do some further reading...

[Spearhead]

A good explanation on TIFF formats and lossless compression can be found <a href="http://www.scantips.com/basics9t.html">here.</a> Summarizing, Emre is right. There is exact recreation of the file with compressed or uncompressed TIFF.

[andrewpgrant]

Okay I think I've worked out where I'm getting mixed up...

 

TIFF files CAN be compressed by a large amount depending on the compression algorithm.

 

However, for all intents and purposes, the kinds of compression algorithms used almost exclusively for our kinds of work (eg. with Photoshop) are the "lossless" ones (which is the point of using TIFF for image files in the first place). Lossless compression algorithms typcally only compress where there is repetitive data, therefore little (if any) compression actually occurs with files such as colour images - which is why we get such huge honking files when working with TIFFs.

 

I apologise for mistakenly bringing these irrelevant forms of TIFF compression into this thread.

[alexdi]

Andrew, I can't tell if you're confused, trying to be right, or clarifying for the original

poster. The information you present is either wrong or misleading.

<p>

<i>the kinds of compression algorithms used almost exclusively for our kinds of work are

the "lossless" ones</i>

<p>

A web designer would beg to differ. JPG, PNG, TIFF, PSD excel in different ways. Lossless

compression isn't always a prerequisite.

<p>

<i>Lossless compression algorithms typcally only compress where there is repetitive data,

therefore little (if any) compression actually occurs with files such as colour images.</i>

<p>

No. This is gross oversimplication. TIFF LZW, PSD, and PNG can achieve 2 to 1 compression

or better on many types of images regardless of content. The algorithms to do as much

are capable of far more than just inserting placeholders. If I wasn't posting on a one-

button iMac, I'd find you a link.

<p><i>which is why we get such huge honking files when working with TIFFs.</i>

<p>The original format makes no difference to working size. Photoshop uncompresses

the entire file to memory regardless. A 3000x2000x32 JPEG is no less strenuous to work

with than a 3000x2000x32 TIFF.

<p>

DI

[andrewpgrant]

>"Andrew, I can't tell if you're confused, trying to be right, or clarifying for the original poster."

 

I am trying to sort this out correctly in my own mind in the interest of learning. I am thinking aloud for anyone who may be following this. I am assuming if I say things that are grossly incorrect, then someone will correct me and we will all learn in the process. I am also willing to be seen to admit that I am wrong as I see too many threads on this site where pointless and destructive arguments develop when people aren't prepared to give any ground - I would like to change that sort of mentality.

 

 

>"A web designer would beg to differ. JPG, PNG, TIFF, PSD excel in different ways. Lossless compression isn't always a prerequisite."

 

I was under the impression that TIFFs using lossless compression algorithms are most relevant to the conversation at hand. This, I believe, is the direction in which Emre pointed me when he corrected my earlier mistake.

 

 

>"No. This is gross oversimplication. TIFF LZW, PSD, and PNG can achieve 2 to 1 compression or better on many types of images regardless of content. The algorithms to do as much are capable of far more than just inserting placeholders."

 

I understand and will not debate this. But since the context of the thread doesn't involve the nitty gritty of how different compression algorithms work, is there any need to not just make generalisations? For example, in a generalised, simplistic kind of way, does an algorithm such as LZW not do something similar to merely compressing repetitive information? This would result in larger file sizes.

 

 

>"If I wasn't posting on a one- button iMac, I'd find you a link"

 

Then learn the hot-keys! ;-)

 

 

>"The original format makes no difference to working size."

 

Okay, but when when you're saving? Saving a file as a TIFF will take more disk space, memory and time than saving as a JPEG (regadless of the compression type used). Size becomes an issue when you start talking both workflow and available memory - this is the case for both workflow AND editing.

 

Likewise, recording an image in-camera as a TIFF will be larger than doing so in RAW or JPEG format and thus will slow things down somewhat when tranferring, opening and re-saving files.

 

If I am still saying grossly innaccurate things, please feel free to correct me. But please, no out-of-context nit-picking.

[jake_holt]

In response to the part of the question, "Colours were all out of whack, image was

washed out, etc..." the problem is, as Beau said, that you need to convert to sRGB

before using save for web. I had this same problem, and it was solved by using this

method. In some cases, the end result was even over-saturated. I'll post 2 examples,

one processed through Save For Web without switching to sRGB, and one processed

after switching to sRGB. Hope it helps.<div></div>

[jake_holt]

Picture #2<div></div>

[alexdi]

<i>Saving a file as a TIFF will take more ... ... memory and time than saving as a JPEG (regadless of the compression type used). Size becomes an issue when you start talking both workflow and available memory - this is the case for both workflow AND editing.</i>

<p>

No.

<p>

Disk save time is a triviality. It's negligible, and the time to compress into JPEG is roughly equal to the additional time it takes to write the larger TIFF file. Same applies to opening.

<p>

Memory use, again, does not differ by format. It doesn't make any difference what format you start and end with in your workflow; Photoshop decompresses and edits the same data regardless.

<p>

DI

[andrewpgrant]

>"and the time to compress into JPEG is roughly equal to the additional time it takes to write the larger TIFF file"

 

That is a good point.

[michael_spencer3]

Michael Maxwell wrote: "... I imported JPEG images from my D70, loaded them in photoshop and immediately converted them to TIFF ..."

 

Well, yes and no. One of the two forms of graphics used with computers is called a "bitmap" and provides a set of color values for each pixel in an image (the other form is a vector graphic). So what I think you actually did was:

 

1) import or "opened" a bitmapped file that originated in your D70 and was saved onto the camera's CF memory using a Joint Photographic Experts Group (jpeg or jpg) compression technique that balanced compression against loss of detail in the image.

 

2) Set up the bitmap in your computer's memory;

 

3) Copied the bitmap to a file in the Tagged Image file format which is identified by the "tiff" or "tif" file extension. (This format was developed in 1986 by an industry committee chaired by the Aldus Corporation which is now part of Adobe). TIF is a lossless uncompressed image file format.

 

My point here is that the "bitmap" is thing you actually want (the contents of the letter) and the file format is merely the envelope. You can drop the letter (image bitmap) into any number of envelopes (file formats). I spelled out the two popular photo formats so you could see the source of their variations. JPEG was created by and for the photographic industry -- creating a smaller package to move around was high on their list of objectives. TIF, however, was created by software applications people to permit the exchange of the bitmap between computer applications. The need to create a smaller package was not stressed. There are many, many other "envelopes" that have been developed to carry the bitmap: Graphic Interchange Format (GIF) was once popular, but its proprietary and subject to royalties. Portable Network Graphic (PNG) was created to replace the GIF without the legal restrictions. etc, etc. On top of all of this is the issue of file compression which applies to ANY type of file on your computer, but is exacerbated by the large size of bitmapped graphics.

 

Putting this altogether: the vast majority of all photographers -- photojournalists and the masses of people who take pictures -- are perfectly happy with the JPEG compromises. And why not? It was developed by the photo industry to serve it and its customers. But there are a handful of perfectionists and hobbyists who need to carefully choose the precise characteristics of the file formats they use to store and transfer their work. That's why this type of thread gets so long.

 

So there are some basic rules of thumb:

 

1. For the perfectionist: do not save your working files in the JPEG format because repeated edit-save cycling will accummulate small artifacts which over time might become noticable. Use lossless file compression techniques only and sparingly.

 

2. For Adobe Photoshop users: save your working files as PSD files to maximize your flexibility while working within the Adobe family of applications. PSD has no compression built in.

 

3. Non-Photoshop applications: use TIF file formats because they are quite old and almost everybody can use them. They are not compressed so if space is not a problem just use them.

 

4. Other needs may dictate some other file format or some other file compression technique. Decide as the facts and circumstances dictate.

 

But as to your actual problem: "Colours were all out of whack, image was washed out, etc..." this isn't really related to the file format and by now you probably wished you had never brought THAT up. Depending upon how perfectionist you are you may wish to bone up on color management techniques. Most folks who have gone through this agree that you need to calibrate your monitor, select appropriate color working spaces, and understand the color characteristics of your particular output devices (different kinds of printers, monitors, and so forth). Plenty on the Photo.net and the internet but not under file formats.

 

Mike Spencer

[andrewpgrant]

>"...file format and by now you probably wished you had never brought THAT up"

 

That part made me chuckle ;-)