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Help with digital camera
Rafter-S
Member Posts: 2,173 ✭✭✭✭✭
I'm wading through the manual on the new Cannon A40 digital camera. I thoroughly understand film photography and film cameras, but am having a little difficulty understanding some to the terms of digital.
In layman terms: Can someone explain "compression" as opposed to "resolution"? I think I know what resolution means, but this compression thing is not made clear.
In layman terms: Can someone explain "compression" as opposed to "resolution"? I think I know what resolution means, but this compression thing is not made clear.
Comments
This is the compression format.
The picture size/resolution has a bearing on you camera's storage ability. If you chose 600x800 each picture will be a smaller file size than if you chose 1200x1400.
Hope this helps.
"If you ain't got pictures, I wasn't there."
Margaret Thatcher
"There are three kinds of lies: lies, damned lies and statistics."
Mark Twain
there is a trade-off between compression and image quality. Less compression, sometimes called Fine mode, gives you better images so you can make larger prints, but you can't store as many images. More compression, in modes such as Normal or Basic, lets you store more images and makes the images better for making smaller prints, posting on a Web page, or sending as e-mail attachments. The only problem is that your prints won't be quite as good. For the highest resolution, some cameras offer an uncompressed format.
One woman's opinion
The finer the compression (superfine mode)will give you better image quality, the small dots that make up a digital picture are much finer and there are more of them per photo. The finer the compression, the more space the pic will take on your camera's memory card. If you plan on printing out 5X7 or 8X10 prints, always use the superfine mode.. I've found the fine mode to be sufficent for 3X5 or 4X6 prints.
Also, do yourself a favor, If you didn't already get rechargable Nimh(nickel metal hydride) AA batteries...get some! This camera eats regular alkaline batteries, I got an Energizer charger and 8 batteries at Wally world for under $30. They will pay for themselves many times over!
Gun control is hitting your target
What "compression" does is remove some of the lesser needed information from the picture to reduce the file size. You can remove some information with little or no loss of overall quality. Unused color shades, stuff like that. TIFs and BMPs tend to be larger files and are not normally thought of as compressed -- they are usually large files and if you were in the advertising business, the print shop would ask you for a TIF file to get a high res copy of your photo for printing.
On the other hand, there are two formats that are compatible, widely, on the Internet. They became popular precisely because their file size tends to be small. One is GIF, suitable more for painted items like icons, signs, cartoons, & non-photo graphics. The other is JPEG, or .jpg, which is a format that allows you to compress your picture on a sliding scale until it is small enough for the internet while still large enough to hold acceptable resolution to see the picture favorably.
When you shoot your pictures, if you're lucky, your camera can save them in any of several modes -- hi res, lower res, maybe even JPEG for the web, which will be the smallest files. People who want to shoot hi res photos for magazine ads need lots of pixels, so they'll buy a camera that has the capability of shooting 3 or 4 megapixel shots, and save them in a TIF-like format (there are many). The software that comes with the camera will probably allow you to convert your pictures to a number of formats for different uses.
Think of "compression" as selectively removing some digital information that is less necessary, or duplicated, or obvious to the computer, in such a way that the software that opens it at the other end can "uncompress" and put back the duplications and re-create the larger image by returning the "obvious" material to the photo as it is opened.
PhotoShop has a neat feature called "Save for the Web" that allows you to view up to 4 versions of a picture you're about to save at different jpg resolutions, high, medium, and/or low. This allows you to pick a rate of compression on the fly by eyeballing your pictures as you save them. JPEG compression quality is literally done on a percent basis. In other words, you can have anywhere from 100% picture quality, which means no reduction in file size, down to as little as say 7% of original file size, meaning a very small file that may be a bit rough to look at.
Obviously, compression is a necessary concern because when using the web, large pictures download slowly. "Optimizing" your photos for the web is an important function especially if you deal with a lot of photos on your website or other web work. JPG is the preferred format for photographs on the web.
There is more to be said about this in the "tips and tricks" line, but this post is too long already. I hope it helped somebody. Ask questions if you're of a mind to.
- Life NRA Member
"If cowardly & dishonorable men shoot unarmed men with army guns, the evil must be prevented by the penitentiary...and not by general deprivation of constitutional privilege." - Arkansas Supreme Court, 1878
Most of my photos will be for sending in email messages...but from time-to-time I will make 4x6 prints of a few.
I may be asking more questions as I get further into the process, if you don't mind. I will try not to be a "pain."
Let's say I take some pictures with my digital camera. I get them home and open them in my photo software and the first one is 600 pixels high x 1,000 pixels wide. It's so big I can't even see it all on my screen at once.
Fine. I'll go to the "Resize Image" command and open the window. It will show the current dimensions, and have a checkbox that says "constrain dimensions" checked. That means if I change the width, the height will change automatically, so that the picture will remain properly proportioned, not "stretched" or "pinched." So all I have to do is change one or the other dimension to a convenient size. No math is involved.
So I say to myself, "when I email this picture, how big should it be for convenient viewing size?" I might decide, well 300 x 500 should be big enough. So I'll change the width from 1000 to 500 and click Okay. Guess what? The picture on my screen is now 500 wide and 300 high, and properly proportioned.
I might change my mind and go back and make the width 600. The height would automatically update to maybe 360 or whatever. Then I click "Save As..." and select JPG format. Boom. I have just saved a copy of the picture as a 360x600 pixel .jpg, and reduced its file size considerably as a result. I can open Windows Explorer, find the file, and see how big it is. It might be 25k or 35k when the original was 600k. If it's too big, I might open it and reduce the image again, back to 500 width or even less.
If the file is still too big at the ideal viewing size, find the adjustment in your software for changing the amount of compression JPG applies. You probably want about a Medium quality setting (50%), but sometimes Low quality (high compression) will do. The commands and terms vary with the software a bit. But with practice, you can create jpgs that are nice sized photos for e-mail or auctions that are 25-50k and fill a mail or browser window nicely.
- Life NRA Member
"If cowardly & dishonorable men shoot unarmed men with army guns, the evil must be prevented by the penitentiary...and not by general deprivation of constitutional privilege." - Arkansas Supreme Court, 1878
Edited by - offeror on 07/17/2002 00:44:13
I stumbled through the setup procedure and somehow got the software loaded (they sure used a lot of terms foreign to a country boy). I had taken a few images the day I got the camera--and before reading the instructions. The camera was set on AUTO, the highest resolution, and super fine compression. I just transferred the images to my computer and emailed myself a message with one of the images attached. It worked!!! But it took a loooong time to send and receive. I now have reset the camera to lower resolution and normal compression. I will reshoot tomorrow and see how that works. Thanks again!
Rafter-S :-)
Every decent software package will give you the ability to Resize an Image. When you pick a new size the software "rebuilds" the photo using a smaller number of pixels and making its best judgments about the coloration of each new pixel, etc., so save your original too for a while until you're sure you like the results.
I've used Paint Shop Pro as well as Superpaint Pro on the Mac and they also have Image Resize. Trouble is, the labels of the commands may be slightly different in each software package, so I can't tell you exactly where to look. You're looking for a window with boxes that gives the dimensions of the image in inches or pixels, where you can change the values by filling in a new number. If you tell us what software you've got one of us can probably tell you where and how the resize works. You'll be looking for the word Image, probably, under the View or Edit menus. By the way, you can also make that image easier to look at by using the Zoom Out feature, but that won't change the actual image size.
- Life NRA Member
"If cowardly & dishonorable men shoot unarmed men with army guns, the evil must be prevented by the penitentiary...and not by general deprivation of constitutional privilege." - Arkansas Supreme Court, 1878
I'm sorry, the direct answer to your question is, NO, you don't need an expensive program like PhotoShop just to resize an image. Any decent photo/paint shop type software package will do it. It's a standard feature and a necessity. The only trick is figuring out how on your particular software package. If you don't like the software you have, go to a site like download.com and pick out something else to try. You might even find a free image editing program that you like better.
- Life NRA Member
"If cowardly & dishonorable men shoot unarmed men with army guns, the evil must be prevented by the penitentiary...and not by general deprivation of constitutional privilege." - Arkansas Supreme Court, 1878
Another question (I feel embarrased to ask dumb questions in public): Can I shoot my images on a higher resolution and fine compression for prints, and then change them in the computer to a lower resolution and normal compression for email?
YES. You can DEFINITELY shoot your pictures as hi-res as you want to, in any hi-res format you want to, and still make them as tiny as you want to for e-mail or the web.
All I have to do is figure a way to get you some decent software tools or some insight into what you've already got .... Let me look into this Picture It thing, and get back to you with a solution that makes practical sense. You may want to download something a little more "mainstream."
- Life NRA Member
"If cowardly & dishonorable men shoot unarmed men with army guns, the evil must be prevented by the penitentiary...and not by general deprivation of constitutional privilege." - Arkansas Supreme Court, 1878
PhotoDeluxe, and probably Picture It, tries to simplify the photo rendering process for consumers with no experience by reducing each process to a series of "simple" steps. I got on my copy of PhotoDeluxe and worked a photo last night. I was able to crop it and then Reduce it, which is what they call the process of lowering the pixels to 72 per inch, which is low res. What you have to do is select each of the tools, and follow the tabs from 1 to 5 for each process, by the end of which you will have successfully applied the effect. You have to experiment. And keep checking your end result in Windows Explorer to see how big your new saved file is.
I don't like this interface because it's actually slower, and the resultant sizes appear to be limited and pre-determined by the software. Besides, 100k is still too big. Even the cropping dimensions are predetermined, and you can only rotate in 90 degree increments -- sometimes you'd like to straighten a picture by 2 degrees or so. But you can reduce the pixels and therefore the file size, using this software.
Or you could get some other software.
One way is to download Kazaalite and use its "napster-like" interface to find something else. Only trouble is, you've got to have good virus protection when you get into file sharing on one of those p2p systems. If you use it very much you will almost certainly be subject, sooner or later, to attempts at virus infection and/or hacking. If your virus software is up to date, it will find and quarantine them before they get a chance to do you harm, but I found it necessary to add a personal firewall as well to ward off a couple of the stickier intrusions.
If you're brave enough to explore kazaalite, here's an informational link. Mirror site 1 seems to work for downloading version 1.7.1 of Kazaalite in English (1.2 meg):
http://www1.kazaalite.com/modules.php?op=modload&name=Downloads&file=index&req=viewsdownload&sid=3
Once you've installed it, use the search feature to find items of interest.
If you'd rather go a more traditional route, go to download.com or shareware.com and find a product, preferably freeware or shareware, like Paint Shop Pro or Photoshop or something more useful for photo editing to try out. Once you have something else, I can be of more help. I've used both Photoshop and Paint Shop Pro extensively. The drill is somewhat different in each, but you don't have to be a rocket scientist and the benefits to you in the long run are vastly better than sticking with PhotoDeluxe.
- Life NRA Member
"If cowardly & dishonorable men shoot unarmed men with army guns, the evil must be prevented by the penitentiary...and not by general deprivation of constitutional privilege." - Arkansas Supreme Court, 1878
Edited by - offeror on 07/18/2002 21:21:29
I have two Nikon F4 cameras with a full set of Nikon AF lenses. With the digital camera, the Nikons will see little use...may even get sold.
Thanks again.