Digikam/Basic RAW Processing/ca

Processament RAW bàsic en digiKam

Transcrit des de l'article d'en Dmitri Popov, l'11 de març de 2013

Per aquest projecte, utilitzarem una fotografia de la famosa catedral de la Sagrada Família a Barcelona, ​​Espanya (podeu descarregar el fitxer RAW des de https://www.box.com/s/cq3uknqt54o3usf1jg3r). La fotografia es va prendre amb una càmera Canon PowerShot S90, i el fitxer RAW presenta diversos defectes obvis, incloent una visible distorsió de barril, àrees subexposades i soroll. En altres paraules, aquest fitxer RAW en particular és perfecte per retocar-lo al digiKam.

Configurant la descodificació RAW

Before you start, make sure that digiKam is set to open RAW files in the 16-bit mode using the default settings. To do this, choose Settings -> Configure digiKam and switch to the Raw Decoding section. Enable the Use the default settings, in 16 bit option and press OK. Open then the RAW file for editing using the F4 key (or choose Image -> Edit).

Aplicant la correcció de la lent

The first order of business is to fix the lens distortion. Since the LenFun library used by digiKam for automatic lens correction doesn’t have a lens profile for Canon PowerShot S90, you have to fix lens distortion manually. Choose Enhance -> Lens -> Distortion, then use the Main slider to set the correction value. Alternatively, you can enter the exact value in the field next to the slider. For this particular file, the -27 value should do the trick. Check the preview image to make sure that the distortion is properly corrected, and press OK to apply the correction.

Utilitzant l'eina de contrast local

Although the Canon PowerShot S90 did a respectable job of producing a well-exposed image, the photo still has slightly underexposed areas. The easiest way to fix this problem is to use the Local Contrast tool (Enhance -> Local Contrast). The default values should do the trick, but feel free to experiment with different settings. But don’t try to push them too far, as the final result may look unnatural. Also, before you start modifying the default settings, save them as a preset using the Save As button. Later, you can restore the original settings from the preset using the Load button.

Aplicant la reducció de soroll

Next stop is the Noise Reduction tool (Enhance -> Noise Reduction). While the default noise reduction settings work fine in most situations, you might want to adjust them to achieve even better results. When experimenting with different noise reduction settings, it’s a good idea to switch to the 100% crop, which gives you a much better view of the noise reduction effect. To do this, select 100% from the Zoom drop-down list. You can then use the scrollbars to view the desired part of the photo. Alternatively, you can use the Pan button in the lower-right corner of the preview window to display a thumbnail of the photo and pan by dragging the red square to the desired area in the image. To preview the noise reduction result, use the Try button.

Definint la fotografia

Finally, the photo could use some sharpening, so choose Enhance -> Sharpen, adjust the sharpness level using the Sharpness slider, and press Try to preview the result. Again, you might want to switch to the 100% crop for a better preview.