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Resolution Confusion

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  #1  
Old 02-10-2004, 04:16 PM
doosume doosume is offline
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Resolution Confusion

Hi, I am new to taking digital photograghs(and this forum). I currently have a Hp Photosmart 620 2.1mp camera that I have been taking photos with and PS 6.0 that I have been practicing retouching in. I just received my wacom Intous2 tablet today!! I have no photography training but do have a web graphics background. Very very basic...


My confusion is with resolution. I have done a lot of reading about it but I am still confused about the fundementals. What would the proper resolution be for a digital picture that I import directly from camera to PS?

Currently, its a 1200+/1600+px - doc sz 17/22 inch - 72 res. I have read on here to uncheck resample image for 8x10 but I don't understand what this does. Or why you do this..

Could someone explain resolution in very basic terms. I am just not getting it.

Also, I am in the market to buy a new camera so that I can take better quality pictures. Does anyone have any recommendations? Or pointers for what I should look for? Ideally, I want to keep it under $1000.00.

Thank you so very much for any advice or information.
Doosume
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  #2  
Old 02-10-2004, 06:38 PM
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catia catia is offline
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Checkout this link

http://www.ltlimagery.com/resolution.html

Catia
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Old 02-11-2004, 07:10 AM
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Doug Nelson Doug Nelson is offline
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First of all, resample changes the image data. It "guesses" what new pixels might be like, so turning it off just makes sure your data doesn't get altered.

Think of your image as a grid. Each square can only be one solid color, and is filled with that color. To have any differentiation between squares, the only thing they can change is the color they're filled with. This differentiation is what gives an image its detail, and the smaller the squares the more of them can fit into your image and the more detail it can represent.

Imagine you're looking at a black and white checkerboard. Up close the squares are obvious, but if you were to back away far enough eventually you wouldn't be able to see the individual black and white squares, and instead you'd see one larger gray square (the checkerboard itself).

Obviously, these squares are your pixels, and the important thing is how many of them there are to represent your image. However, since images vary in size, they're standardized by how many will fit in an inch. This way they can be discussed independently of what the image is. This is very useful, but also causes some confusion, since pixels are kind of abstract at first, but everyone knows what an inch is.

The answer to "how many pixels is good" is simply: more is better. However, it's useless if the pixels are artificially filled by resampling (see above). Having your camera or Photoshop "guess" to fill in pixels will do nothing to improve image detail, and can actually hurt it. That's not to say resampling doesn't have it's place, but just that it's not between the camera and Photoshop.

So, in your camera, don't fret about the "pixels per inch" part. The only thing that matters is how many total pixels are involved. In your case that's 1200 x 1600 pixels.
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Old 02-11-2004, 12:28 PM
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T Paul T Paul is offline
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Understanding Resolution

Resolution can be a confusing topic. I did some web research on your questions and came up with the following links that may be helpful:

Understanding Resolution - Nature photographers.net

Understanding Resolution -luminous-landscape.com

Understanding Resolution -Espresso Graphics.com

Understanding Resolution- Williams Photographic.com

Basically this is what they said:
Quote:
Doing the Math
To understand digital image size you simply have to understand that pixels are more tightly packed for printing than for display on a computer screen.

Computer monitors display images at 72 ppi (pixels per inch), meaning that there are 72 pixels for every 1 inch of linear screen space you see on your screen. Therefore, if you have an image on the screen that is 720 pixels wide, it will take up 10 inches of linear screen space (72 dpi x 10 inches = 720 pixels). This may look beautiful on the screen, but if you try to print this image on a printer at 72 dpi the result will look extremely choppy.

To get a good looking print from your printer in many cases you'll want to print at 300 ppi (pixels per inch), which means that the 10 inches across the screen will be reduced to only 2.4 inches on paper (720 / 300 = 2.4, or 24% of the original 10 inches). The result is a smaller, but much cleaner, image on paper. So a good rule of thumb about how physically big an image will be on paper is that it will be about 25% or one quarter of it's size on your screen.

Lets say for example you have an image that is 1200 x 1200 pixels and you're going to print that image on a printer.

It would take a screen 16.6 inches wide to display the image at full size.
1,200 pixels ÷ 72ppi = 16.6 inches

On paper that same image would be 4 inches wide.
1,200 pixels ÷ 300ppi = 4 inches

Common Image Sizes and Print Sizes at 300 dpi
Image Size 4064 x 2704.....Megapixels 11.1.....Print Size 13.5 x 9
Image Size 3088 x 2056.....Megapixels 6.3......Print Size 10.25 x 6.8
Image Size 3008 x 1960.....Megapixels 5.3......Print Size 10 x 6.5
Image Size 2048 x 1536.....Megapixels 3.0......Print Size 6.8 x 5.1
Image Size 1600 x 1200.....Megapixels 2.0......Print Size 5.3 x 4
Image Size 1280 x 960......Megapixels 1.2......Print Size 4.25 x 3.2
Image Size 640 x 480........Megapixels 0.3......Print Size 2.1 x 1.6

Megapixel and print size values are rounded off.

Last edited by T Paul; 02-11-2004 at 03:40 PM.
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Old 02-11-2004, 12:32 PM
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T Paul T Paul is offline
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Quote:
Originally Posted by doosume
My confusion is with resolution. I have done a lot of reading about it but I am still confused about the fundementals. What would the proper resolution be for a digital picture that I import directly from camera to PS?
Well that is going to depend on what you plan to do with it (web, print, etc) and if printing, what size you are looking for (5x7, 8x10, etc).

Resolution is one of the most commonly misunderstood attributes of electronic images. Too much image resolution and your Web page loads slowly, too little and the quality of printed media suffers. The secret to determining proper resolution lies in the understanding of how it is measured and where the digital image will be used.

Resolution Settings
Set your camera for the highest resolution possible. Many cameras have settings such as "Standard," "Normal," "High Quality" or "Super High Quality." Check your manual to determine the specific resolutions these terms represent. Depending on your camera, the resolution settings could range from 72 ppi to 300 ppi. A 72 ppi image is fine for viewing on a computer monitor; 300 ppi is the generally the resolution required if an image is headed for the printing press.



~From the Web

What resolution you need for a digital picture depends on what you plan to do with it. You'll need a high resolution for printing, depending on the size and quality you need, but high resolution is less important for web images. Higher resolution can, however, make it easier to crop or reframe pictures without losing detail.

How much resolution you need is determined by the size of the images you'll be creating. If you're only going to make 4 inch snapshots of your images then you don't need a lot of resolution. But if you're taking pictures that you want to blow up significantly then you want as much resolution as you can get. You can change this number depending on how "grainy" you want your image to look. Most Web images are only 72ppi to keep file sizes small so they'll load quickly. For digital photos you want to output your images around 300ppi.

Resolution Affects Output
Most digital cameras allow you to change the resolution setting, so you can fit more or fewer images on your memory card. This can be a helpful feature if you only have one card or if you are on a trip and can’t transfer photos to your computer. But if you take a photo of a spectacular sunset, and you capture it on a lower resolution setting like 800x600, you may be unhappy with the result if you want a 5x7 or 8x10 print. That’s because the low resolution image lacks detail, and may also appear jagged.

Carrying additional memory cards and keeping the camera set on its highest resolution setting is a better solution. The higher the photograph’s resolution, the more plentiful printing and sharing options exist. With this in mind, the best bet is to shoot photos at the highest resolution your camera can capture. The resolution can easily be adjusted downward on your computer later to adjust for the various outputs such as email, web and various print sizes. However, there is a limit to how effectively photo resolution can be adjusted upward by a computer. This means, for example, you can always make a sharp, clear, small print from a high-resolution photo, but you can’t make a rich, detailed, large print from a low-resolution one.

Last edited by T Paul; 02-11-2004 at 12:58 PM.
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  #6  
Old 02-11-2004, 12:43 PM
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T Paul T Paul is offline
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Resampling

Quote:
Originally Posted by doosume
Currently, its a 1200+/1600+px - doc sz 17/22 inch - 72 res. I have read on here to uncheck resample image for 8x10 but I don't understand what this does. Or why you do this..

~From the web....
Resampling Definition: The resample command is used to increase or decrease the size and/or resolution of a bitmap-based image. An image is upsampled to increase the resolution by adding new pixels. An image is downsampled to decrease the resolution by throwing out pixels.

Resampling an image usually results in a loss of image quality because pixels must either be interpolated or thrown out. The exception is when the resolution of an image is changed without modifying the pixel dimensions. For example, an image with pixel dimensions of 1200 by 1600 can be printed at a size of 4 x 5.3 inches at 300 dpi or at 8 x 10.6 inches 150 dpi. Reducing the resolution while increasing the print size does not result in image destruction, but it will result in a loss of print quality.

When the Resample Image box is checked, any changes you make to an image's width or height will not change the image's resolution, and as such, any changes you make to an image's resolution will not affect the image's width and height. Keep in mind, however, when you increase width and height, or resolution, you are adding pixels to your image. These pixels don't actually exist so Photoshop must create them. As such, you will succeed only in degrading the quality of your image.

If you want to increase an image's width and height, or resolution, then uncheck the Resample Image box. Now any changes you make to the image's width and height will change the image's resolution, and vice versa:
If you decrease resolution, the width and height will increase.

If Resample Image is checked when the image size is altered, resampling usually takes place, resulting in pixels being added or deleted.

Increasing the pixel dimensions (file size) results in the creation of brand new pixels based on existing tonal/colour values. Large increases in size, four times the current size and upwards, leads to dithering on the edges of images, obvious pixelation, lack of sharpness and loss of detail.

Reducing the pixel dimensions (file size) results in the removal of pixels. Extreme reductions have no detrimental visual effects, provided the resolution is appropriate for a given use.

Any resampling involves interpolation, a process of assigning colours to pixels. The method of interpolation can be altered to suit a particular image. Bicubic gives the best quality; Nearest Neighbour retains sharp edges within images and is appropriate for certain graphic subjects.

Steps
To set output resolution in Photoshop select Image > Image Size from the menu.

Now uncheck the Resample checkbox and set the document resolution to the desired setting. Many recommend 360 dpi for the best quality. You'll just have to experiment here to determine what quailty to want. For instance, sometimes 150 dpi is fine for inkjet prints, othertimes, you may want to go with a higher resolution like 300 dpi.

By setting the output resolution with the resample option disabled, the output size will automatically change to show you the largest possible output size at the resolution you’ve set, without any interpolation.

Now set the actual output size you want. Your image may allow you to produce an 8”x10” print without interpolation. If you only want your print to be 5”x7”, you’ll need to reduce the size of the image, throwing away pixels.

To do this, simply check the Resample checkbox again, and set the desired height or width. Be sure the Constrain Proportions checkbox is checked so that the image won’t be distorted. Then, when you adjust either the height or width, the other will be adjusted automatically to fit.

Once you have the document resolution and output size, simply click OK and the image will be resampled. Keep in mind that if you changed the size of the image, pixels will be added or removed by Photoshop.

While this can be done to a reasonably degree without losing too much quality, the quality will suffer to at least some degree. For that reason, I strongly recommend that you save the original image before resizing it. If you want to save the resized image, select File > Save As, and save it as a separate file.

Last edited by T Paul; 02-11-2004 at 03:43 PM.
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Old 02-11-2004, 12:55 PM
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T Paul T Paul is offline
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Quote:
Originally Posted by doosume
Also, I am in the market to buy a new camera so that I can take better quality pictures. Does anyone have any recommendations? Or pointers for what I should look for? Ideally, I want to keep it under $1000.00.
It all depends on what you want to do with your photos? Many recommend a minimum of 3.2 megapixels for general shooting. More if you want to do serious shooting or if you think you might want to print some of those images at 8x10 or larger sizes.

~From the Web
The advantage of having a camera with a higher resolution is you have more pixels to work with. One answer comes when you think of a high-resolution picture as a combination of low-resolution pictures. In other words, having more pixels gives you more options for zooming, cropping, or framing the shot. That's important when getting prints made.

In general more resolution means better print quality. It also gives you an advantage if you need to crop the image. Cropping is when you only use part of the image for the final print. It also gives you an advantage when creating larger 5x7, 8x10, or bigger prints. The more you have to blow an image up the more any defects will start to jump out. Starting with a higher resolution image means there's less magnification necessary to get to a given print size. For example, if you have a five-megapixel (2560 x 1920) image, you can cut off up to 960 pixels off the sides and up to 720 pixels off the top or bottom to make a 2-megapixel picture. This lets you zoom in on the important part of the picture, or center it differently.

Quote:
Small Prints - 1 Megapixel.
Step up to a megapixel camera and you will find a grid containing upwards of 1152x864 pixels. Theses cameras allow you to produce a good quality, 4x6 inch print with a photo realistic printer.

Getting Larger. - 2 Megapixel.
Further up the scale are the 2 megapixels digital cameras. Standard 2 megapixel cameras will give you good 8x11 pictures. Obviously any 4x6 or 5x7 prints should be more or less pin sharp with two megapixels.

Getting Larger and Enhanced Quality. - 3 Megapixels.
Once you reach the 3 megapixel bracket the quality of print is normally excellent up to 8x11. The cameras often offer a number of features associated with 35mm SLR cameras and manual override of the automatic settings are more common, allowing you greater artistic control as you get to know your camera and want to experiment a little.

4, 5 and 6 Megapixels.
Lately we have seen the introduction of 4, 5 and now even 6 megapixel digital cameras. Image quality is exceptional and prints beyond 8x11 are available. Cameras in this range come equipped with the latest state of the art features. Some of the benefits at this level are: Increased standard storage capacity but be aware that a single high resolution image at this level could consume 16mb of storage. Optical lenses generally around 5 times. Burst mode. This is the ability to shoot more than one image for just one click of the camera. Typically around 3 frames per second for six frames. Greater aperture range. A greater range of ISO settings. Historically digital cameras have performed less than perfectly in darker settings. The greater range of ISO settings gives a big improvement.

Digital SLRs.
If you have a very large wallet or take you digital photography very seriously then there are an increasing number of Digital SLRs to tempt you. Many are becoming quite affordable, and if you want the capability of changing out lenses and increased control this is a great option for you!
A great web site for camera reviews is Digital Photography Review.
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Old 02-12-2004, 04:10 AM
doosume doosume is offline
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Thanks

Thank you Catia, Doug Nelson and T Paul for the information and for taking the time to explain it for me!!

For now, I would like to focus on getting great 8x10s to print. I don't have a lot of money to throw around so getting the best picture at lowest price is what I need. You have given me a great second starting point for my research!!

Once again, I thank you all for taking the time to answer!
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