Qns on resizing photos


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Chys

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#1
Hi all, I normally take my photos at my camera's maximum capability, which is 2272 x 1704.

Earlier I was trying to resize them using various different softwares and found that ALL of them somehow "made" the photos more blur (than before) after resizing. How can I resize without "blurring" the image?
 

megaweb

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#2
Most of people will use Adobe Photoshop to reduce the image to viewable size like 600x400. Usually after reduce the image size, you should apply sharpening to the image. Try to use Unsharp Mask .
 

leadwe

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#3
For cropping of photos, how do you resize to fit a 4R ratio?
 

Madmax

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#4
leadwe said:
For cropping of photos, how do you resize to fit a 4R ratio?
In photoshop, you can use the crop tool with dimensions 6" x 4". That is 4R size.
 

blurblock

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#6
Chys said:
Hi all, I normally take my photos at my camera's maximum capability, which is 2272 x 1704.

Earlier I was trying to resize them using various different softwares and found that ALL of them somehow "made" the photos more blur (than before) after resizing. How can I resize without "blurring" the image?
Resizing as in making it smaller? That should not happen, unless you set the compression rate (we will take it you use JPG) to very high, thus dropping a lot of details.
 

leadwe

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#7
Do I crop first, then resize? It's possible to get distortion in way right?

Or can the cropping tool be pre-set to crop only in ratio of 3:2?
 

blurblock

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#8
leadwe said:
For cropping of photos, how do you resize to fit a 4R ratio?
I cheat a bit, in Photoshop, I open a new window of 6 x 4 (inch), the I copy the whole picture into the new window. :D ..... after that I use "move" tool too shift the picture until the composition I want :D.
 

blurblock

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#9
leadwe said:
Do I crop first, then resize? It's possible to get distortion in way right?

Or can the cropping tool be pre-set to crop only in ratio of 3:2?
Both ways are applicable, depending on what you want to do with it.
 

r52lanc

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#10
blurblock said:
Resizing as in making it smaller? That should not happen, unless you set the compression rate (we will take it you use JPG) to very high, thus dropping a lot of details.
Resizing always blurs the image. It reduces noise but blurs. You have to sharpen after resizing. Sharpening should always occur after resizing in your workflow.
 

megaweb

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#11
leadwe said:
Do I crop first, then resize? It's possible to get distortion in way right?

Or can the cropping tool be pre-set to crop only in ratio of 3:2?
Why do you need to resize? you mean for resize to smaller image for web viewing ? Usually I will crop > resize > sharpening

For printing, just crop to 6:4 or 4:6 ( same as 3:2 or 2:3 ) ratio is good enuff. Of course you need to do some sharpenings before you send your shots for printing.
 

espn

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#12
Agree with mega, resize for web viewing is fine, but not for printing. For printing I'll send in the files as is. TIFF or JPEG, of course provided the shop doesn't scream at you for 30MB TIFF files... heehee.
 

Virgo

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#13
To add to what espn has mentioned, for 4R, just put to 6"x4" (or 4"x6") at 300dpi and you should get enough details for the prints
 

leadwe

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#14
Sorry prob I didn't make myself clear. What I'm asking is that after cropping, the photo is normally not zun zun 3:2 ratio. To send for printing, I would need to resize it. Which function of photoshopt should I use then?

Sharpen as in unmask sharp? I tried that but can see no difference, at least not on my monitor.
 

megaweb

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#15

ThomasD

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#16
Virgo said:
To add to what espn has mentioned, for 4R, just put to 6"x4" (or 4"x6") at 300dpi and you should get enough details for the prints
My camera always record image at 72dpi no matter whether the image is recorded in big or small size. What happen if you increase the resolution to 300dpi using PS? If image is recorded at 72dpi, how then can I actually increase the resolution?? :think: :think:
 

Tzuen

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Jul 29, 2004
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#17
Thomas the dpi resolution doesn't really matter, the pixel resolution does. Only worry about print size and dpi when you have to print.
 

#19
ThomasD said:
Let's say I need to print out the photo, does increasing the dpi from 72 to 300 affect the quality of the picture?
Basically 72 dpi is about the general resolution for looking at the picture on your PC screen only. Which in most cases is fine on your PC and can look pretty sharp especially when certain software also has specially feature to blend the pixels to give it an enhance and more pleasant look on your screen.

But when you are printing out by way of a Colour Printer, 72 dpi is too coarse and will result in pixelation which translate into seeing a lot of jaggy lines and edges when printed out in 72dpi. By using Photoshop to change the picture's resolution from 72 to 300 dpi is not going to help the situation to improve. It is just the same bad situation only at a higher dpi only. You can take a 300dpi picture and readjust to view it on the PC by setting it to 72 dpi but never the other way around. To some extend it might help only if you take the size into consideration as well. That is about the only time maybe it can help your situation if you want to change it from 72dpi to 300dpi.

For example I have a picture that is 72dpi and it's size is about 24inches by 36 inches. Now you might already know those sizes does not make sense much on the PC monitor as your program will scale it down to fit your PC screen. In the real world outside the computer if you do try to print the picture at it's given value of 24x26 inches and AT 72dpi...you will find the picture would look really bad!..as there will be a lot of jaggy pixels. Now at this point you might say...okay, let's increase the dpi from 72dpi to 300 dpi that should solve it yes? Since the printer can print at 300 dpi too. Nope! Increase the the resolution from 72 to 300dpi just increase the SIZE of your picture file from say 2mb to maybe 8mb! but not the quality. The concept is very simple in graphic sense. A big picture can be shrink and it will still be fine and sharp but you can not take a small picture and increase it size and get MORE details out of it. Your picture must in the first place contain enough details and information so that it may be enlarge and still give you all those details missing when it was a small picture. Problem is those details are not like magic and pop out of no where. :) Don't believe all that BS in the movies where you see some super spy or some army defense using a power camera or satellite camera to shoot an image photo and then they bring it to some lab where they would look at the picture and then have the ability to zoom in tight to some blur looking area of a print and then add more resolution to it or enhance it with a computer program so that missing or blurry details actually start to appear. The truth is if your original picture...film or digital lacks the details to begin with...there is no way you could ever get more out of it. No technology is that smart to be able to predict or manufacture it. The only way that can be true is if the designer or artist paint the image!

So how and when can you actually set the resolution from 72 dpi to 300dpi and get some "quality" out of it? Well I would not say quality but I would say the picture will look more acceptable and sharp since you will also be reducing it's size. SO getting back to my above example of 24 x 36inches at 72dpi. I will now choose say to print that picture in 8x10 print size. So I will use Photoshop to change the picture size. I will choose 300 dpi and select 8x10inche for the new size.( see again it is about reduction and using a smaller image size) Now with the new size it looks fine. In truth nobody really would print 72 dpi on their A4 printer right. Usually folk or software will scale it down to A4, maybe regular 3R, 4R or 10R. The PC might actually select 300dpi once it rescale it down to one of those sizes I just mentioned. But when would this situation not be workable? It is when the size is already 3R for example and the dpi is already at 72. You can print it out as 3R size but the quality will be very bad as the dpi is too coarse for printing and the printer will print it pixel for pixel in size! In that situation, trying to change the dpi from 72 to 300 but keeping it at 3R size will not make a difference. It just use bigger print size dots to preproduce those same 72dpi dots on your 3R size picture. It is abit hard to explain it but I hope roughly it gives you abit more idea as to why changing from 72dpi to 300 dpi in most situation will not make a difference in the final printing.

That is why when designers do design production or photo shoot, we try to get the graphic done in as higher a resolution and size as it allows. And when we know the photo we shoot will be use to make larger sharp poster and other large scale prints later on, we will try to use medium format nagatives or those larger format camera to produce those large negative that can hold more details and resolution. So that there is flexibility for reproduction work later on.

Just my two cents... :)
 

Tzuen

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Jul 29, 2004
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#20
Sammy's post was quite confusing to me, let me see if I can state this clearly.

There are 2 sets of values that you need to worry about when printing a photo. Pixel dimensions and Document size. All these values can be tweaked under Image Size in photoshop.

Lets use these figures for the example. Lets say your image out of the camera is : Pixel dimensions : 1800 x 1200 px and Document Size : 25 x 16.667 inches at 72 dpi.

When you take a picture, it is basically made up of tiny squares of information containing 1 color, like a mosaic tile design. Seen from a distance or if they are tiny enough, a image appears made by the pattern. These tiny squares are known as pixels.

These pixels can be printed as a certain document size. In fact almost any document size. The resolution in dpi(dots per inches) mean just that. Uncheck the the resample image dialog box. try changing the resolution to 100 instead of 72. Notice how the document size is now 18x12 inches. The pixel dimensions do not change. You have a fixed number of pixels to work with. 100 dpi means that each 1 inch square of printed image contains 100 pixels of information. Thus increasing the resolution (in dpi) means getting more information per square inch and thus a less grainy image.

Doubling the resolution to 200 means halfing the document size. Try it. The document size is now 9 x 6. Notice that when you do not resample an image file, the pixel dimensions do not change.

What happens if you want to print a picture at a document size AND resolution higher than what your pixel dimensions can support? This can be done with resampling the file to a larger pixel dimension. This technique is called interpolation. Interpolation basically runs a program to guess how to enlarge a picture. You are basically adding information where there was none. The program analyses the patterns of the pixels to determine how to fill in the missing spaces when the image is expanded. For example. If a red pixel is surrounded on 8 sides by red pixels it can guess that when enlarged it will still be surrounded by red pixels. This guess work is not fool-proof and will make mistakes. These mistakes, usually at edges of two or more colors result in a soft (looks out of focus) image. The higher the magnification of the original image you wish to make, the more guess work and thus mistakes the program will make.

Back in our image, lets set the final document size to 12x8 inches. Notice how the resolution is only 150 dpi. Assuming we want to print this at 300 dpi, we must interpolate the image to get the pixel dimensions to achieve this. Check the Resample image box. Now change the resolution to 300 dpi. Notice how this doubles the pixel dimensions. hit Ok and the image is interpolated.

The easy way to do all this is to use the crop tool in photoshop. Just set the document size and resolution and let photoshop downsize or interpolate as needed. Just be aware that trying to print a image larger than your original pixel dimensions will mean the need to interpolate and will result in a "softer" image.

A last tip, always sharpen your picture last, after resizing. Goodluck.
 

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