Compress TIFFs using ZIP of LZW

[alan_markowitz1]

Hi all,

Haven't seen a recent discussion on this topic. Is it safe to compress TIFF

files in ZIP or LZW (using Photoshop of course). Could this cause any problem

with image quality at any point? I saw some old threads about image corruption

when compressing. Are these problems of the past?

[obakesan]

Hi

 

compressing TIFF with ZIP or LZW is no different to compressing a text file or other document with the same things (have you used software like winzip or stuffit expander?)

 

Just as your word document never looses any words or formatting when compresses neither does the image.

 

Now, JPG is a different ball game. JPG uses a compression style which is designed to recreate the image you gave it with a new set of data. The exact values of pixels luminance or indeed perhaps even the exact pixels themselves are never recoverable. JPEG redraws the image in a way which the designers intended that you would not be able to "see" the difference.

 

Depending on the compression levels this might be more easily seen, or perhaps (if the intention is only quick glances) not notice.

 

HTH

[rainer_t]

If a tiff file uses lzw or zip compression, you don't lose any quality, since both are lossless compressions. But you lose a certain amount of compatibility with other programs, since not all programs, that accept tif-files in general, are able to work with these compressions.

[Ed_Ingold]

It is not very useful to compress TIFF files. The size reduction is not very great, and is often done at the expense of redundancy and check-codes. Secondly, compressed TIFF files are not very portable - they can't be opened in many other programs. Finally, it takes a lot of time to compress TIFF files, and time is what it's all about.

[kelly_flanigan1]

The LZW comprssion is lossless. This file variant is one of the many hundreds of TIFF vairants. Its not *openable* by all programs; check before sending it to a chap on a tight deadline thats using unknown software. <BR><BR>For *photos* typically its not worth fooling with; the compression ratio is small.<BR><BR> For *signage, billboards, brochures* is used more. The compression can be ALOT when there are simple tones; ie wide open spaces with all one color; or just a few. Photo books and gurus often preach that LZW is useless; often it is for photos. For printing; a 60 meg poster/sign layout can be compressed down to say 1 megs often; and emailed to podunck on dialup. Or it can be a direct modem to modem connection to a digital sign on a freeway; where the few megs of uncompressed file are sent by a dedicated phone line; and the LZW file is only say 100 to 250k in tiff LZW. <BR><BR>In engineering drawings there is a FAX format called group 4 tiff that compresses single bit images a radical amount. This file variant of TIFF does back into the 1980's. A 30x42 inch 1 bit image is 24 megs uncompressed. With a typical scan of clean engineering drawing; the Group 4 TIFF might range from 100 to 700k; a dirty drawing or one thats muddly with alot of background speckle might scan in say from 1 to 3 megs. We were scanning images like this with a 386 in the 1980's; and posting them on out 14,400 bps BBS for customers. Our first 28.8 modem was something like 320 bucks. Later we had a ISDN line for 600 per month; that was 64K up and down; cool beans. With dialup and todays cable/dsl; compressing a 24 meg file to 250k with no loss still works and saves time with engineering drawings; or even signage/layouts. For photos typically compressions with LZW is small; not worth it.

[mendel_leisk]

I agree with the other responders. If you weigh the benefits vs risks, Tiff compression hardly worth it. Where are your files coming from: scans of film or digital slr? If scans, they likely will not compress much, due to grain. If dslr raw, just retain the raws, they're much smaller anyways.

 

As hard drive capacities and optical disc formats evolve, todays problem will soon seem superfluous.

[patricklavoie]

Well, im not agree at all.

 

It is well worth it to compress your TIF using LZW, first it doestn take more time (or sligthtly maybe) in some case my file reduce form a 100meg to a 20meg file (if they contain a lot of white, like a portrait over a white background).

 

Secundo, for storage it could not be a problem, but when i upload file via FTP, it make a major difference if my file are 100, 70, 50 or 20meg.

 

Also, a LZW TIF is compatible with anything i could think of as today, from word to illustrator, and indeed photoshop.

 

So saying that compressing a TIF hardly worth it, that the compression ratio is small etc...is not true.

 

I as a professional alsways save my TIFF as LZW before sending to my client, and a lot of time a save from 25% to a blazing 60% of fiel size doing it.

 

So it is safe? yes

 

Could it affect quality? no

 

Problem of the past? i personally never had any problem opening any old TIF LZW i had as today.

[kelly_flanigan1]

Here I have seen folks miss deadlines due to using LZW Tiffs. <BR><BR>When folks ask for LZW on a CD; I burn some uncompressed ones too. I have had to drop everything several times to email; FTP; FedEx files to get customers out of a pickle. <BR><BR>One can just zip the uncompressed TIFF files too and avoid a disaster.<BR><BR> In an old direct modem to modem situation or many uploads there is compression that can take place with uncompressed files; an not with compressed ones. In some cases the compressed ones take longer. <BR><BR>LZW is not universal; its like talking in jive talk instead of plain annnouncer/broadcaster English. Its great and quick if you know all your receivers of you data; but is not understood by all. It runs on a subset of software. Do you feel lucky?<BR><BR>12 years ago there were over 200 variants of TIFF. Our 65 thousand dollar printer thats 6 months old wont accept LZW in all file sizes; it will in some; and not others. Thus these files are converted in a batch program; abit cool when there are many hundreds in one wad and the batch takes a few hours if its a hotel or major project. One has a batch that opens the bastard LZW Tiff; and resaves it as a plain TIFF.<BR><BR> One of our older poster printers wont take LZW tiffs; versions of Autocad wont; older Photoshop wont; somc older canned freebie imaging programs wont either; it shows up as a bblack image in some browers; or not at all.<BR><BR> In printing if one has say 45 TIFFS to a job on a high speed printer as a set; maybe #28 sheet is a bastard LZW. With a D size 24x36 print they are shooting out the back at 12 to 15 prints per minute as B&W image. The bastard file LZW then creates an error sheet to be printed; as short one. Then the whole damn job restarts and sometims the print stacker/collector gets a foul with his dinky sheet; and the 12 to 15 sheets per minutes then create this massive paper mess; often it goes inot the trash. Digital = scrap?:) One has monitors to watch the printers; one can either kill the job via runnning to the printer; or trying the VNC link on another computer; and prey the LAN has little delays; or is up! <BR><BR>Thus the unknown customers job is often watched abit more; preflighted for BS; and often batched to non-LZW them; or to eliminate delays due to poor structure. With one chaps PDF's; each 36x36 color print takes 15 20 minutes before the print even starts; tying up the printer. Thus the file is ripped and a saved in a form that takes the printers controllerr only a minute to seconds to mess with; instead of 1/4 hour. Often folks have layers not needed; fonts that have to be sorted out.<BR><BR>With a Mac's TIFF's; if these image are inserted into autocad wtih the Mac byte order; sometimes all is well witht eh autocad user with the TIFF image as a layer. But when saved this non PC TIFF as layer in a PC's autocad file or PDF can creat a weird file thats printable; but it takes mabye 15 minutes instead of 1 second to process

[patricklavoie]

Kelly, you talk about a 12 years odl printer, a old photoshop version, autocad, ...all must have been true in the past, but i send regular job evryday month to hi end fshion magazine and many other stuff to commercial printer and i have bever seen that TODAY to be a problem.

 

Plus, i think that whe extrapolate the subject a bit, even me, because the OP ask if it does a difference or if he will see a quality problem, for those question the answer is NO. And im sure that with todays tools and software it will not be a problem to save a TIF, not in a 45 flavor compression format but as a LZW(= (im agree do that saving it in a ZIP compress format part of the TIF saving dialogue could cause problem in many software other than PS)

[kelly_flanigan1]

No I talk about a brand new printer that cost 65,000 dollars and was bought last May. Thus with the few LZW filess we get we must delay the chaps job because we have to convert then to a plain TIFF, PCX etc. 2007 is not the past; even in a digital world. The pouint about LZW not being able to be read in 2007 by all programs, rips, browsers etc is true. In printing for the public we probabaly see on thousand times the types of file variants that a typical photographer, graphics arts chap, cad operator uses. These exceptions can cause delays as the files have to be kicked out, converted etc. <BR><BR>The same thing goes for fonts; each customer has certain fonts. In their little narrow minded world everybody else has the same fonts; so why embed them or actually mention what the fonts are.<BR><BR>The poinyt is that an amateur can assume stuff; have delays, assume that everybodys programs and rips can convert LZW or has the same fonts. They make images for the fun of it; there are no deadlines; nobody to answer too; ones neck doesnt get rung by assuming things will magically work.<BR><BR>Usage of LZW ccauses a delay in opening and closing a file. In rips a LZW tiff takes longer since it has to be converted before the rip process; its a subprogram.<BR><BR>Its common for folks to work with one printer; one client and LZW works; then they have a rush job and the files are sent to client #2 and there is a delay becuase they cannot open them. I have seen this happen many dozens of times in the last 2 decades; even in 2007. <BR><BR>Assuming that all programs and rips and browsers can read LZW is like assumming there is one type of razor blade, ink cartridge, cellphone battery. Its like buying a new camera and they assuming a store in Java will magically have a spare one; ie assuming.

[patricklavoie]

there's more than one kind of razor blades?! dam, i didtn know it ; )

 

Kelly i got your point, maybe then the guy i use converted the file everythime then?

 

thanks for the explanation.

 

BUT if the OP stay in is little world, is printer, is minilab..would you be agree that LZW will not change visualy the quality of is images, and will not cause him problem? basically if is not going on press, it should not be any problems, right?