 Cyndee Wanyonyi |
Explain, please...JPG in laymen's terms Okay, there are few things that I don't quite understand about digital photography/manipulation. In laymen's terms, will someone please tell me the "simple" difference between the jpeg and RAW? I also want to know what it means when I resize photos in Photoshop 3.0. Does this mean that it will print/save differently (i.e., a larger print of the picture will have less resolution??*&^>)? So confused... AND...if I have a client that wants very large photo (canvas, 3.5 ft x 4 ft, or something similar), should I use my film camera or can I shoot with a Canon XT Rebel (8.0) and still get nice results?
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x |
You asked too many questions, but I'll answer the first. RAW allows for more manuipulation in post processing. JPEG doesn't have the same latitude for manipulation, so you have to correctly expose in camera. Jerry
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Andrew Laverghetta |
I'll go for the rest and an elaboration on the first as well. Your camera has the image chip on it....it captures data. Each pixel will captures something like 1 color of light. So, you put all those little dots together and you get your big picture. JPEG processes the data the image sensor picks up so if "100100110" means "this pixel is green" the computer might save it as "green" instead of that "100100110". That number is just an illustration though. RAW is essentially the "raw" data, unprocessed, that comes straight from the sensor. Since the data hasn't been messed with, that means it is easier to change the color cast on the picture like if you shot in artificial light, you can make the light look more natural. When you open your image in photoshop especially as RAW, it might say the size is something like 35inches by 30inches at 72dpi. It is at 72dpi so you can view it easily on your computer screen and there aren't any pixels going to waste. Most computer moniters only display at 72dpi anyways. If you're picture is 100dpi, only 72 will be displayed on the screen. If you're going to print the image, you will probably want to use the CROP TOOL in photoshop and set the dimensions to something like 4x6inches at 72dpi and it will be more fit for display on the internet. It also takes up less space on the internet and opens faster. Also, after you scale it down like that for the internet, you will want to select SAVE AS under the FILE menu at the top and save it as JPEG under where you will type the file name. Set the quality to the highest number so when it's compressed it won't lose any information/quality. Just to wrap stuff up, if you are going to print something, crop it to the size you want it but set the dpi to 300dpi instead of 72 because 72dpi won't be enough to look good on paper. So, for the internet: 72dpi. For printing: 300dpi. Some people also reduce the dpi to 200 when they print images larger than 20x30inches because they won't be viewing it close up as compared to 8x10inches. If somebody wants a print that is THAT big, you might want to go with a low ISO, low grain film so make sure it's good quality. Your camera would also make a pretty good image though. I'm sure it would look good with the digital as well. Ask the people at your lab where you will be getting this done more on the specifics and what they think. As the actual technician if you can. Since it would be on canvas, the resolution may not need to be as high. This would definitly be a time when you could use 200dpi instead of 300dpi. dpi means dots per inch by the way, just wanted to make sure. You can never ask too many questions by the way. Feel free to contact me through my premium gallery. You should find a link to it at the top of my post here.
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Michael H. Cothran |
Let me throw in some simple laymen's understanding - if you want the finest quality enlargements, shoot RAW, and do all editing in PS. Resizing is when you change dimensions and ppi proportionally. Resizing does not change or affect the file size. If you change one or the other or both non-proportionally, it will change the file size, and PS will introduce bicubic interpolation (meaning it has to add pixels to your image). This will ultimately deteriorate your image quality. Finally - give up on the 3.5' x 4' print from your Rebel OR your 35mm film camera. "Nice results" just ain't gonna happen that big! For ultimate "nice results", contain your enlargements to 13x19" or less. You can squeeze out a 16x20, or maybe even a 18x24, but you're going to see major deterioration in image quality as you enlarge - and if you don't size properly with PS's bicubic interpolation, it will be even worse. If you want large prints (with nice results), you'll need a 16 MP or 22 MP camera at the least. Michael H. Cothran www.mhcphoto.net
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Josh Hudson |
I really hate to have to clarify stuff that other photographers have put out, but I think it is important. The RAW file is the image as it is recorded by your chip without any commited processing. This means that you still have 'raw' data. When you shoot JPEG (A processing system designed by the joint photographers expert group and owned by compuserve) you have commited the image to being processed and then compressed. The advantages to shooting JPEG are that if the image was shot properly, your color and exposure on the mark, you have a readily finished picture ready to print. The disadvantage is if you have made an error on the color or exposure, you have lost a lot of information and have less latitude for correction. Also, since the JPEG is compressed each time you save the image to save space, you are discarding small amount of information. Which means the image will degrade over time. There are ways around this and other processed formats (like TIFF) that protect your images from degredation. So as you can see RAW gives you the chance to process your images for color on the computer instead of the camera. You also have a 2-4 stop exposure latitude to save poorly exposed images. However, this also means that you have a lot of work to do on each image later on. And since RAW images are proprietary to each camera system, you may need special software to work with the images. What RAW will NOT do for you is afford you a higher quality image for resolution. The highest resolution JPEG is the same pixel size as the raw file. If your camera allows for uninterpolated images of 8x10 at RAW then you get the same for your highest level JPEG. There is also a misconception on the sizing of the images. You only need 100-144 dpi image to print a photo at photo quality. This means if you have an image that is recorded at 3000x2000 pixel image, you divide that by 100 and you get a 30x20 (conventially we use 144 dpi and that means 20x14 sized prints). Since most 6MP cameras shoot around that range, you will get a 20x14 inch image without interpolation from any Drebel, D70, D100 or other 6MP camera on the market. The reason files are kept at 300 dpi is for archiving. With the assumption of use with files like JPEG (Which will degrade eventually) and people who want to have some "play" in their image enlarging and cropping, they double the dpi (dots per inch) for their files. Joshua Hudson
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Andrew Laverghetta |
Then why do labs request that you send them a photo at 300dpi for printing rather than 100-144? And then 200 for larger prints? It just seems like that's just skimping by with the least amount of resources. As for the image quality of one being better than the other, I'll do my own tests even though I've seen better quality on similar tests between RAW and Large/Fine JPEG.
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Josh Hudson |
It is a safety factor more than anything. You can test as much as you like. But pixels are pixels. If you shoot a 3000x2000 pixel raw file and a 3000x2000 pixel jpeg file, you will get the same images sizes in your prints.
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Andrew Laverghetta |
I wasn't saying images size though, I was saying more about the edges of curved lines and greater definition.
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Josh Hudson |
you are talking pixelization. That is based on the pixel count. Same exact thing. If you shoot the same photo at the same resolution and print from the same crops AND you process your raw images to have the same exposure and color balance as the JPEG....there will be a 0% percent difference. In fact, if you match up the color balance and exposure settings to the jpeg, you just did what the camera did to the raw file to make the jpeg to begin with. The only time definition between to exactly same raw and jpege images will change is over time when you open and close that jpeg over and over and start loosing information. But for the first 100 openings or so..they are the same image.
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Matthew Slyfield |
Josh, You can open and close the jpg all you want. The image quality only degrades when you re-save over the original file. Each time you re-save the jpg the compression is re-run causing more data to be lost. However, if you open the jpg and close it without editing or saving, then the file does not change and the image does not degrade.
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Andrew Laverghetta |
This is what I was talking about. http://www.dpreview.com/reviews/canoneos300d/page11.php It's part of the review on the Canon EOS 300D/Digital Rebel conducted by dpreview.com. That part that The thing I notice here is how the numbers on the watch face look a lot more definite in the RAW capture than the JPEG directly beneath it.
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Ganesh G |
So, Whats the final verdict? RAW or JPEG or TIFF ? I am mostly interested in having my photos on the computer. I might take an occasional print of a meduim size. Let us say, a 4" x 6" or a 8" x 10". Whats the best selection for me. And where can you set the DPI in the digital cameras? I am thinking of buying the Panasonic Lumix FZ-10. Its a 4MP camera with a 12x optical zoom.
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Josh Hudson |
DPreview is not showing a RAW file when they show a RAW example. This is because you would probably not be able to view the image. That RAW file is a JPEG and processed after the fact in Photoshop. So all of Dpreviews examples of RAW vs. the Highest JPEG are erroneous. After shooting digital professionallyy since 1996 and teaching digital photography in college, I can tell you that RAW and JPEG at the same pixel size show no resolution difference. Now, with that being said, why is there confusion? Well a lot has to do with settings. In DSLR cameras you can set the in camera sharpening for your JPEG. If you oversharpen you can "clip" the images which will give a more pixelated look. When you shoot RAW you have no settings that apply. You open the file in your RAW file software the original raw file is open and it is up to you to adjust and process the image. Usually, if you have a good RAW software you can get better sharpening, color correction, etc. But a perfectly focused, exposed, and white balanced shot will show no difference between RAW and JPEG. If you are keeping your images on your computer you should convert those jpegs to TIFF so that you have a lossless file media. When you are shooting for yourself and confident on your shooting technique, then you can shoot JPEG and never worry about RAW. There are no setting for DPI in your digital camera. Dots Per Inch (DPI) is a printing output and you need to make those settings on the computer before sending to the printer.
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x |
Amen, Josh. I get so tired of people saying RAW is better, without considering the fact that they produce a JPEG when they go to print. It's just silly. I have friends, who are pro photographers, who say RAW is better, but I know what they mean by "better". I'm not always convinced that other folks knows what "better" means. It doesn't produce a better print. In certain circumstances, it might be a better choice than letting your camera process the image. It depends on what you are doing, but it has nothing to do with print quality. Jerry
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- Gregory LaGrange Contact Gregory LaGrange Gregory LaGrange's Gallery |
Prints can come from tiff.
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William Koplitz |
Yep, correcting people is a bummer, .jpg doesn't have anything to do with Compuserve, Compuserve developed .gif http://www.jpeg.org/
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Josh Hudson |
Sorry William. JPEG was developed by Forgent Networks (formally known as VTEL). You are right. But they were hit in the news last year trying to collect royalties based on the COMPUSERVE lawsuit from a few years previous over GIFs.
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William Koplitz |
Just as I wrote, compuserve developed .gif It wasn't the file that had the patient but the compression, LZW, the algorithm used to store the image data within GIF, was patented by Unisys. I don't know what you are sorry about.
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