As the old saying goes "Less is More."
This is certainly true when it comes to certain images. Cropping an image can eliminate distracting elements, improve composition or even shift the focal point to a different area of the image. Today's image editing software makes cropping images relatively painless. An image can be quickly copied and cropped. Any cropping applied to the copy can be quickly undone as long as the copy has not been saved.
This process can be repeated to create any number of images, each with an alternative crop.
Tips for Cropping Images
1) Use an image program with transparency and layering capabilities.
This allows you to place a cropping stencil above your image. This stencil is basically a frame with a transparent square or rectangle cut out of the middle. The part of the image visible is what will remain after cropping.
2) Prepare stencils with desired aspect ratios in advance.
Start with an image equal in size to images produced by your camera. (This does presume you want to crop photos.) Fill with a single color, black works well. Enable transparency if not already enabled. Create a second layer on top with a different color.
Decrease the scale of the top layer. The aspect ratio can be altered if desired. Merge the shrunk layer with the first. Use the color selection tool to select the middle area and cut. (The editing software I use places the layer in the middle of the image when shrunk. If second layer is placed at a corner you will have to move it. The placement does not have to be precise.)
3) Save file using format that preserves transparency.
Saving using the editing software's native format should do this. Exporting to png format is an alternative as this saves transparency settings. Other formats will result in the transparent area being replaced with the background color.
Stencils with different aspect ratios can be saved as different files or images. They can also be saved in a single file as different layers. Make sure each file or layer has a description of the aspect ratio.
Using a crop stencil
1) Import Stencil
Open the image you want to crop in your image editing software. (Again, it needs to support transparency and layers.) Follow by importing the appropriate stencil.
If you saved the stencil as as individual files, just open the desired stencil as a new layer.
If all stencils are saved in one file, open that file then copy the desired stencil. Paste this on top of the image as a new layer.
The stencil can be moved around once it is on top of the image to be cropped. This helps give a good idea of what the cropped image will look like. The stencil can also be rotated to change orientation or scaled up or down to change how much of the image will remain after cropping.
2) Select Transparent Area
Use an area selection tool targeting the transparent area of the stencil. Make sure the selection tool is set to select transparent areas.
3) Use Selection to Crop Image.
The quickest way to do this is simply selecting "Crop Image to Selection." The image can be saved with a different name after this so that the original image remains unaltered. Of course, the quickest way is not always the best way.
An alternative method is to copy the selected area and then paste as a new image. This image will have a different name from the original so there is no chance of overwriting the original file. The copy and paste method works well if uncertain that the selected area is the best choice. The original file still has the stencil in place and this can b quickly altered if the crop is not quite correct.
The stencil can still be used if the software refuses to select transparent areas. Select the colored portion of the stencil instead. Switch to the image's layer. Then invert the selection.
Why Not Just Use a Rectangular Selection?
This may seem like unnecessary work when you could just use a rectangular selection tool to select the area you want to keep. There are some reasons to use a crop stencil when cropping images.
First, it's easier to tell what the end result will be when using a stencil to block out portions of the image. Using a selection by itself will require a certain amount of guessing as to how the crop will turn out.
Second, using a stencil results in an accurate aspect ratio after the crop is applied. This is useful in some circumstances. The most obvious reason for using a specific aspect ratio is because the image will be printed and framed. The aspect ratio changes based on the size of print desired.
A 4" x 6" print requires a 3:4 aspect ratio. An 8" x 10" is a 4:5 ratio. Compare the lengths as percentages to understand what that means. The first ratio results in the short side having a length 75% that of the longer side. The second result in the shorter side having a length 80% as long as the longer side.
Using an image with a 3:4 ratio to print an 8" x 10" requires one of two options. First, the image can be stretched in one direction. Second, the print can have blank borders along two edges.
Cropping the image before allows the image to be printed without choosing one of those options when printing at a specific print size.
Friday, September 27, 2013
Monday, September 23, 2013
Technology - Image Sensor Size
Camera manufacturers love to tout the number of megapixels offered by their camera, but never seem to mention the sensor size. Finding information on the size of the sensor used in a camera usually requires delving into the technical specifications, and the description may be a bit obscure.
When a manufacturer describes their sensor as an "APS-C" sensor, they are referring to its size. The problem is, that size differs based on manufacturer.
Why It Matters
The size of the image sensor determines the surface area available for collecting light. More light generally translates into higher image quality. This means a large sensor can produce higher quality images than a smaller sensor even if the smaller sensor boosts a higher number of pixels.
Increasing pixel count without changing the size of the sensor requires decreasing the size of the individual pixels. (More accurate, it requires the size of the area used to capture light referred to as a photosite.) Smaller pixels increase image noise, especially in low light conditions.
Sensor size does impact camera design. Larger sensors require larger lenses. This in turn requires larger camera bodies, making larger image sensors impractical for phones and compact cameras. Larger sensors also cost more to manufacture. Manufacturers use smaller sensors to keep costs down.
The smaller target area provided by smaller sensors impacts the lens used. Using a lens designed to be used with a larger sensor will result in part of the image falling outside the surface area of the sensor. Part of the image seen in the viewfinder will be lost. Smaller sensors require wider angle lenses to properly focus the image onto the sensor.
Sensor Sizes
he largest sensor size found in consumer level cameras are known as Full Frame sensors. These have the same dimensions as 35mm film. Lenses designed for 35mm film cameras will work exactly the same if used with a camera using a full frame sensor.
Next in size are APS-H sensors, followed by APS-C sensors. The size of the latter depends on the manufacturer.
Next in order of size comes 1.5", Micro Four Thirds 4/3", 1", 1/1.2", 2/3", 1/1.7", 1/2.3" and finally 1/3.2". The use of fractional divisors makes some of the sizes a little hard to understand. (Really, 1/3.2"?)
This makes the relative size a little easier to understand. A 1/3.2" sensor is almost 5 times smaller than a 1.5" sensor. It get's a little more confusing when attempting to compare the "inch" based measurements to full frame and APS sized sensors. The inch based measurement actually refers to the size of the lens, not the diagonal measurement of the sensor. This increases the size given by about 50%. (Multiply the given figure by 2/3 to get the approximate diagonal size of the sensor.)
Full frame and APS sensors only provide mm measurements for size. To make comparison a little easier, according to my calculations full frame sensors are the equivalent to 2.77" in the above system. APS-H and APS-C sensors fall between 2.555 and 1.5. APS-C is roughly 1.8" and APS-H roughly 2.1".
For a visual depiction of related size try this gizmag sensor size guide article.
Wikipedia has an article on Image sensor formats that includes a list of sizes at the bottom, including diagonal dimensions.
For those that are interested, manufacturers do make cameras utilizing sensors larger than full frame sensors. The next step up are referred to as medium format cameras. Large format cameras use even larger image sensors.
The width and height of medium format sensors are roughly 50% larger than that of full frame sensors. (In "inch" terms, roughly 4.3".)
Medium format digital cameras are used by many professional photographers. These sensors offer up to 80 megapixels. Combining this number of pixels with the larger sensor size provides image quality unmatched by most consumer cameras.
In addition to the above "inch" system, the sensor's surface area will also give consumers a good idea how sensors compare to each other in regards to image quality. A medium format sensor has a surface area of over 2100 square mm. Full frame is 860 square mm. APS-C ranges from 330 to 380. A 1/3.2" sensor has a surface area of just 15 square mm.
The extremely small surface area available for that last sensor results in it being far less capable of capturing existing light. It is going to be far more reliant on good lighting conditions than the larger sensors. This doesn't mean the camera will be incapable of taking good pictures, just more reliant on existing light. (My old Kodak EasyShare ZD 710 has a 1/2.5" sensor. It takes excellent macro flower pictures in full sunlight.)
When Buying a Camera
The impact sensor size has on image quality means that consumers should always consider sensor size when purchasing a new camera. The problem is that sensor size data is not always easy to find. The only source may be the manufacturer's web site. The manufacturer should mention the sensor size on the specifications (spec) page for each camera model.
Online stores generally include camera specification on the product page. Check the specs when shopping online.
Brick and mortar stores may be a bit more problematic. The material provided may not list sensor size. Check online if not available at the store.
When a manufacturer describes their sensor as an "APS-C" sensor, they are referring to its size. The problem is, that size differs based on manufacturer.
Why It Matters
The size of the image sensor determines the surface area available for collecting light. More light generally translates into higher image quality. This means a large sensor can produce higher quality images than a smaller sensor even if the smaller sensor boosts a higher number of pixels.
Increasing pixel count without changing the size of the sensor requires decreasing the size of the individual pixels. (More accurate, it requires the size of the area used to capture light referred to as a photosite.) Smaller pixels increase image noise, especially in low light conditions.
Sensor size does impact camera design. Larger sensors require larger lenses. This in turn requires larger camera bodies, making larger image sensors impractical for phones and compact cameras. Larger sensors also cost more to manufacture. Manufacturers use smaller sensors to keep costs down.
The smaller target area provided by smaller sensors impacts the lens used. Using a lens designed to be used with a larger sensor will result in part of the image falling outside the surface area of the sensor. Part of the image seen in the viewfinder will be lost. Smaller sensors require wider angle lenses to properly focus the image onto the sensor.
Sensor Sizes
he largest sensor size found in consumer level cameras are known as Full Frame sensors. These have the same dimensions as 35mm film. Lenses designed for 35mm film cameras will work exactly the same if used with a camera using a full frame sensor.
Next in size are APS-H sensors, followed by APS-C sensors. The size of the latter depends on the manufacturer.
Next in order of size comes 1.5", Micro Four Thirds 4/3", 1", 1/1.2", 2/3", 1/1.7", 1/2.3" and finally 1/3.2". The use of fractional divisors makes some of the sizes a little hard to understand. (Really, 1/3.2"?)
| Converted To Decimal Form | |
| 1.5 | 1.5000 |
| 4/3 | 1.3333 |
| 1 | 1.0000 |
| 1/1.2 | 0.8333 |
| 2/3 | 0.6667 |
| 1/1.7 | 0.5882 |
| 1/2.3 | 0.4348 |
| 1/3.2 | 0.3125 |
This makes the relative size a little easier to understand. A 1/3.2" sensor is almost 5 times smaller than a 1.5" sensor. It get's a little more confusing when attempting to compare the "inch" based measurements to full frame and APS sized sensors. The inch based measurement actually refers to the size of the lens, not the diagonal measurement of the sensor. This increases the size given by about 50%. (Multiply the given figure by 2/3 to get the approximate diagonal size of the sensor.)
Full frame and APS sensors only provide mm measurements for size. To make comparison a little easier, according to my calculations full frame sensors are the equivalent to 2.77" in the above system. APS-H and APS-C sensors fall between 2.555 and 1.5. APS-C is roughly 1.8" and APS-H roughly 2.1".
For a visual depiction of related size try this gizmag sensor size guide article.
Wikipedia has an article on Image sensor formats that includes a list of sizes at the bottom, including diagonal dimensions.
For those that are interested, manufacturers do make cameras utilizing sensors larger than full frame sensors. The next step up are referred to as medium format cameras. Large format cameras use even larger image sensors.
The width and height of medium format sensors are roughly 50% larger than that of full frame sensors. (In "inch" terms, roughly 4.3".)
Medium format digital cameras are used by many professional photographers. These sensors offer up to 80 megapixels. Combining this number of pixels with the larger sensor size provides image quality unmatched by most consumer cameras.
In addition to the above "inch" system, the sensor's surface area will also give consumers a good idea how sensors compare to each other in regards to image quality. A medium format sensor has a surface area of over 2100 square mm. Full frame is 860 square mm. APS-C ranges from 330 to 380. A 1/3.2" sensor has a surface area of just 15 square mm.
The extremely small surface area available for that last sensor results in it being far less capable of capturing existing light. It is going to be far more reliant on good lighting conditions than the larger sensors. This doesn't mean the camera will be incapable of taking good pictures, just more reliant on existing light. (My old Kodak EasyShare ZD 710 has a 1/2.5" sensor. It takes excellent macro flower pictures in full sunlight.)
When Buying a Camera
The impact sensor size has on image quality means that consumers should always consider sensor size when purchasing a new camera. The problem is that sensor size data is not always easy to find. The only source may be the manufacturer's web site. The manufacturer should mention the sensor size on the specifications (spec) page for each camera model.
Online stores generally include camera specification on the product page. Check the specs when shopping online.
Brick and mortar stores may be a bit more problematic. The material provided may not list sensor size. Check online if not available at the store.
Ricoh's Pentax K-50: Customizable Camera Colors
Tired of owning that DSLR camera that looks like every DSRL camera? Ricoh has you covered with its K-50 DSLR camera. Its appearance can be customized by altering the colors of the components of the camera's body.
There are 20 options available for the main body (purple above) and 6 for the grip.
Customizing the camera's look does not cost extra, but does require 4-6 weeks for delivery from Ricoh. There are pre-designed options that include colored lenses as well.
The K-50 is also weatherized, making it a good choice for outdoor photography. It uses a 16.3 MP CMOS sensor and a Pentax KAF2 mount for the lens.
Customizing the camera's look does not cost extra, but does require 4-6 weeks for delivery from Ricoh. There are pre-designed options that include colored lenses as well.
The K-50 is also weatherized, making it a good choice for outdoor photography. It uses a 16.3 MP CMOS sensor and a Pentax KAF2 mount for the lens.
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