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Frequently Asked Questions and Answers
Bitmap file type
Mar 20, 2021 16:42:41   #
Rongnongno Loc: FL
There are several file type that exist in the photographic field. Each has it advantage and issues.

The most common file types are:

Mar 20, 2021 16:43:00   #
Rongnongno Loc: FL

DNG (Digital NeGative) has been created by Adobe to create a standardization in 2004. It has not taken hold.

Some cameras create DNGs instead of raw files. This is why DNG is confused with a raw file.

You can encapsulate JPG, raw, TIFF, PNG from any source.

This is an issue as when using a DNG, if you do not know what it really contains, you may be working with a lesser format like a JPG or a PNG.

Advantages of the DNG format
 • While not a standard the DNG format allows many program to use raw files that would not otherwise be editable
 • It SHOULD be used to stop the JPG file degradation.

 • It is not a standard but is widely accepted
 • DNG content is not consistent since it can encapsulate many bitmap formats

Mar 20, 2021 17:26:11   #
Rongnongno Loc: FL

First let's get rid of the myths.
 ► False: JPG are harder to edit. There are limitations compared to other file types. Said limitations are not making editing harder.
 ► False: Compression is cumulative when you view a file. I do not know when and where this myth started but if your eyes can damage something just by looking at it, let me know.
 ► False: JPG are better than raw files. JPGs have very little potential compared to a raw file. JPG has all the camera setting applied when a raw file does not. This creates limits when editing.

JPGs are an ancient standard format, granted. JPGs are reliable and accepted universally.
JPGs can be shared quickly due to their acceptance and relatively small size (in kb).

What influences a JPG quality:
 ► Amount of details. If an image has many details the JPG cannot be reduced all that much and keeps most of the detail intact.
 ► Compression ratio. The greater the compression the more data loss.
 ► Cumulative compressions. When editing a JPG the data is decompressed but conserves the artefacts. When saving after an edit these artifacts are compressed again so cumulative.
 ► Areas of the same color or with a slight gradient. These will compress well but at the price of banding.

Now, unless you are pixel peeping, it is unlikely you can detect the compression artifacts, but banding might become visible.

Original JPG

JPG edited with rawtherapee and saved as JPG.

Right click on each image to compare.

Mar 26, 2021 00:33:19   #
Rongnongno Loc: FL

“Portable Graphics Format”

About the PNG format
 ► Like JPG PNG is a WEB standard.
 ► Was made to replace the GIF format.
 ► Supports transparency.
 ► Does not support animation. APNG does.
 ► Uses a lossless compression
 ► Supports different color spaces
 ► Supports a color depth up to 64-bit per pixel (Scientific use)
 ► Maximal size in pixel is 2,500 Megapixels. By comparison JPG is 65,535 pixels (Scientific use)

Please note that PNG compression is irregular, meaning some programs are good and create smaller files when others create larger sizes for the same file, all being lossless.

The definite guide to PNG. For the techies...

Mar 26, 2021 09:57:31   #
Rongnongno Loc: FL

“Tagged Image File Format”

About TIF Files
 ► Is a WEB standard
 ► Originally create to create page layout
 ► Is a container and can include vector graphics.
 ► Is owned by Adobe after purchasing it from the Aldus Corporation
 ► Lossless compression
 ► Is layered and suitable for high color rasterized images
 ► are usually larger than other graphic file formats
 ► File limit is 4 GB
 ► Color depth is 32 bits
 ► Can be offered as an in-camera option

I would not suggest anyone to select TIF over raw in-camera. There are no advantages, only drawbacks. Between the size and the loss of some information there is no point.

Mar 26, 2021 10:33:54   #
Rongnongno Loc: FL

A raw file is a file produced by a camera sensor.

About raw
 ► Proprietary, not only in brand but also within a brand (Different in each camera model)
 ► Uncompressed and lossless compressed
 ► Bit depth depends on the camera sensor array it is far superior to the camera produced JPG yet can appear duller at first.
 ► Retains but does not use the camera settings other than: Focusing plane, DoF, Speed (blur)
 ► The embedded JPG thumbnail quality depends on the JPG settings - even if JPG is not used -.
 ► Demands a new approach to exposure. (UniWB, ETTR, EBTR...)

 ► sraw is a joke, do not use it. This is a lossy format first in recording the sensor array data, then by using a lossy compression. The only dubious advantage is that it is smaller.
 ► Early camera adopters will experience a delay before the software is upgraded to the new format
Software will use the camera settings included in the raw file initially (WB, Color space) among others. While technically raw does not use it, software to edit does but can be easily overridden.
 ► A raw file is the best option to exploit the potential of a camera sensor array.

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