Image Compression Formats

[aimeeandbeatles]

This one I think is too much question and thus worth its own thread.

A lot of you know my work saving articles and stuff so thats what Im leaning to, not photos or whatever. So keep it in mind.

Most of the time I use PNG images which work well for my needs. Though somebody else told me that I should actually be using TIFF ("it's better", they werent real specific) which I really dont know too much about. Should I believe what they say or are they trying to make me look like a fool?

Also, within the next week or so Im gonna be scanning a magazine article (as of yet I don't know if it's color or greyscale on the inside) with my scanner. Here are the formats available:

BITMAP (.bmp)
JPEG (.jpg)
Multi-TIFF (.tif)
PDF (.pdf)
PRINT Image Matching II (JPEG) (.jpg)
PRINT Image Matching II (TIFF) (.tif)
TIFF (.tif)

Theres no PNG available which is what I normally use. And Im not sure what "PRINT Image Matching II" is though it sounds something propriety so I think I should avoid it.

Thirdly, if an item is originally in greyscale, should it be scanned in greyscale?

 

[SuperJay]

1) TIFF vs PNG: The PNG format is generally going to be better image quality for online use, in part because the compression reduces file size drastically. TIFF is only useful if you're planning to print the images, and if file size is not an issue - TIFs can be quite large.

2) I don't really know what your question is here. You might want to Google that "PRINT Image Matching II" thing. Also, look up your scanner manufacturer and model, there's usually documentation online for these things.

3) Yes, there's no reason to scan for color if your document doesn't contain any color.

Really, you can just Google "TIFF vs PNG" or something like that and find plenty of information about the suitability of various image formats to different purposes.

This may help: http://www.wfu.edu/~matthews/misc/graphics/formats/formats.html

 

[Zelig]

Tiff is the archival standard.

 

[aimeeandbeatles]

Well I googled it but a lot of it has to do with photos and not the sort of thing I do. If you dont understand what Im doing, see an example of it here. Note that the actual image files are usually 2-3 times larger (pixel, not filesize) larger than what I have online, I shrink it for reasons of bandwidth.

I tried looking up that weird Print Image Matching thing but I dont understand what its for. And I said I'd prefer to avoid weird formats that might not work on a website.

This is exactly what my scanner documentation says:

BITMAP (*.bmp) (Windows only) Standard image file format used in Windows. Most Windows application including word processing application can read and prepare images in this format.

JPEG (*.jpg) Compressed file format. The compression quality can be selected; the JPEG format enables relatively high compression ratio. However, the higher the compression ratio is, the lower the image quality becomes. (Note that the original data cannot be restored.) In addition, the quality deteriorates every time the data is saved. The TIFF format is recommended in cases where modification, retouch and the like are required. You can add ICC profile (information on color reproducibility of scanned image) to the image.

Multi-TIFF (*.tif) TIFF format where multiple pages are saved to the same file. When you scan documents using the Automatic Document Feeder or multiple scanning, all scanned documents are stored in the same file. (With other formats, each document is saved in a separate file.) However, to open the Multi-TIFF files, you need an application supporting this format.

PDF (*.pdf) Document format that is independent of platforms. When you scan documents using the Automatic Document Feeder or multiple scanning, all scanned documents are stored in the same file. When you save color or grayscale images in PDF, you can select a compression quality.

PICT(*.pct) (Macintosh only) Standard image file format for the Macintosh. Almost all of the software applications for the Macintosh (such as word processing software) support the PICT file format. [This ones not available]

PRINT Image Matching II (JPEG) (*.jpg)/PRINT Image Matching II (TIFF) (*.tif) Print Image Matching is a standardized method of recording a wider range of color information to enhance the quality of your scanned images. Using a printer compatible with PRINT Image Matching, you can effortlessly achieve printouts that come to life with a dynamic range of brilliant colors.
Note: PRINT Image Matching information does not change the image data or the way the image is displayed on a computer screen.

TIFF (*.tif) File format created for exchanging data among many applications such as graphic and DTP software. When scanning black & white images, you can specify the compression type. You can add ICC profile (information on color reproducibility of scanned image) to the image.

Bitmap, I think, is the most versatile but Ive seen those and they're freaking huge, several megabytes for one image. I think its uncompressed (like WAV for sound).

 

[mdwh]

I don't know of any advantages of TIFF over PNG. PNG is lossless, so quality isn't an issue.

 

[cardgame]

PNG is high quality and more universal than tif

 

[Earthling]

PNGs are pretty good, and I don't know enough about the differences between PNG and TIFF to make a specific recommendation. I think it's one of those things where if you know the software or someone else you're working with prefers or works better with TIFF that'd be the reason to use it, just for consistency, if not PNG is very common/universal. All I know is that in this day and age of ever faster machines and connections hopefully we'll see a trend away from worrying about overly lossy compression on things anyway. JPEG2000 is a bit better but man screw the DCT.

 

[dragokatzov]

I just save everything in a jpeg. works well for me

 

[mdwh]

Regarding the scanner formats - if you don't want to use a lossy format like JPEG, I'd use bitmap or TIFF, then convert it to whatever your preferred format is. (AFAIK both bitmap and TIFF have the support for some limited compression, you might have to just test it to see which works out smaller file size in practice.) Any competent software/operating system ought to be able to cope with a range of formats - god knows why they need PICT just for Apple users.

If retaining 100% quality isn't essential (and you won't be repeatedly editing the files), JPEG is usually fine.

I find PDF handy for scanning documents, as it's easier to read multiple pages as part of the same file.

 

[aimeeandbeatles]

Well I usually turn my articles into PDFs anyways so scanning it directly to that would save time I think. But Im not sure how the quality is. Its an Epson Scan 3.4A the software is and theres not much for PDF quality options.

I forgot to mention. There also various modes for scanning. Theres a very basic "home" mode, a slightly more advanced "office" mode (which is what I normally use) and an advanced "professional" mode that I dont understand half the options. But the "home" mode also have preset settings for magazines -- should I try that?

 

[The_J]

Yes, try it. It it's bad, then just try it again. It's not so that anything could go horribly wrong, right ?

Maybe some technical background details could help:
.bmp: It's what the name says. A bit map. For every bit the RGB values and the light value are saved. Everything is saved = the file is big.

.jpg: Loses some information, because in the range of 3*3 pixels only the 4 RGB values of the edges and the light value in the middle is saved, the rest will get interpolated by the program (that makes it look blurry).

.png (just looked it up, saw the same question some time ago and wondered): Saves the same information as a .bmp, but uses a compression algorith similar to .zip (so theoretical opening one should need more processing power than a .bmp, but file size is smaller).

.pdf: I assume the images are saved there as .svg (scalable vector graphics). That means for lines a beginning point, a direction and the length is saved. That is a) lossless b) scalable (not blurry when zooming; yeah, the name is a hint...) c) needs less space on the hard disk than a .bmp.

.tiff: Looked it up too...whoa, no idea.


So if space is not a problem, then save it as .bmp, and convert it to whatever you want.

 

[aimeeandbeatles]

My magazine just came in AND THERES COLOR PICS!!!!!!

EDIT: I forgot to mention. Im doing it in Bitmap then use IrfanView to save as PNG. Does this sound the best?

 

[cardgame]

PNG is the best image format IMO, but jpeg saves a lot of room if you're tight on space.

 

[enneagon]

Just a word about .tiff - it's old as a world (developed 1986-1992, extended till today), have had almost no real alternative for long long time, and many artists, photographers, publicists and other people stick to it, sometimes for completely mystic reasons.

.tiff stands for Tagged Image File Format, or for joke Thousands of Incompatible File Formats
That means, it has huge versatility, along with dozen or so lossless compression formats, u can put even jepg within a tiff. It supports both byte orders, and u can save alpha channels, vector masks, layers, save in CMYK color, save more than 8 bits per channel or even floating point images for scientific use. And lot more.

Use it to save high quality, high color-depth images u known to need edit and re edit for hundreds of times and print poster sized in the end.


For Your current needs, maybe that not the best idea, but if u not concerned about exact color precision but wants smallest file size possible, test the old good .gif with reduced color table.