Abrir archivos

[javierp94672301]

Hola, al abrir un archivo fotografico que pesa 250KB desde PS, al ver tamaño de la imagen la muestra como de 2,2MB. Alguien sabe por qué ocurre ésto?

Muchas gracias.

[JJMack]

In the file the image data is encoded and compressed in memory the image data decoded and uncompressed.

[c.pfaffenbichler]

What file format is the image exactly?

[javierp94672301]

.jpg is the format. This image for example:

[c.pfaffenbichler]

jpg employs lossy compression (in general) and can significantly reduce files’ sizes depending on the content and the degradation one is willing to accept.

[javierp94672301]

Ok, thank you, but can it go from 250 KB to 2.2MB? or is there something in the PS configuration that allows me to maintain the weight of the image?

[JJMack]

Its like having 1000 euro coins  or having a 1000 euro bill.  In either case you have 1000 euros.   

[javierp94672301]

Sorry JJMack, but 250KB = 0,25MB

[JJMack]

Its 250KB of encoded and compressed data on disk = 200MB of umcompress and decoded data in menory.

Compress bank note in your bank account heavy coins in your pocket. Different formats of the same thing.

Encoded and Compress your image can not be displayed. You can not put you bank account in you pocket you must first change the account into coins.

[javierp94672301]

Well, now I understand, thank you. If so, is there any way that PS does not decompress the data?

[JJMack]

The depends on the image file format you are saving you document into.    Jpeg standard is lossy compression and has a quality setting that changes how lossy. Each jpeg generation losses some image quality.  Jpeg does not support layer or transparency. Some Image file format  support lossless compression  and can also be saved uncompressed.   Beside image data image files can contain other data metadata and color profiles.

If the file is not compresses there is noting to decompress.  There is no way to display an image if the data is compressed.  Even uncompressed the image data needs to be decoded and convert into the data structures Photoshop uses.   Image viewers also need to decompress and decode image data to be able to display an image.

[javierp94672301]

Thank you very much for your explanation, it has been Un. very helpful.

[JJMack]

Image data is mostly pixels data.    However you have to know how to decode that data.  How many bits per pixel.  The number of pixels the aspect ratio of the image the color space there is a lot of bit level processing that need to be done to display and image.  That information is in the images header so you can decode the pixel data.