ImageMagickを使うとコマンドで簡単にフォーマット変換ができます。
インストール
brew install imagemagick
使い方
以下のコマンドで変換は完了です。
画像の種類は拡張子を見てうまく判断してくれるようです。
convert test.jpeg test.png
対応フォーマット
コマンドで確認したらかなりの種類がサポートされていました。
$ identify -list format
Format Module Mode Description
-------------------------------------------------------------------------------
3FR DNG r-- Hasselblad CFV/H3D39II
AAI* AAI rw+ AAI Dune image
AI PDF rw- Adobe Illustrator CS2
ART* ART rw- PFS: 1st Publisher Clip Art
ARW DNG r-- Sony Alpha Raw Image Format
AVI MPEG r-- Microsoft Audio/Visual Interleaved
AVS* AVS rw+ AVS X image
BGR* BGR rw+ Raw blue, green, and red samples
BGRA* BGR rw+ Raw blue, green, red, and alpha samples
BGRO* BGR rw+ Raw blue, green, red, and opacity samples
BMP* BMP rw- Microsoft Windows bitmap image
BMP2* BMP -w- Microsoft Windows bitmap image (V2)
BMP3* BMP -w- Microsoft Windows bitmap image (V3)
BRF* BRAILLE -w- BRF ASCII Braille format
CAL* CALS rw- Continuous Acquisition and Life-cycle Support Type 1
Specified in MIL-R-28002 and MIL-PRF-28002
CALS* CALS rw- Continuous Acquisition and Life-cycle Support Type 1
Specified in MIL-R-28002 and MIL-PRF-28002
CANVAS* XC r-- Constant image uniform color
CAPTION* CAPTION r-- Caption
CIN* CIN rw- Cineon Image File
CIP* CIP -w- Cisco IP phone image format
CLIP* CLIP rw+ Image Clip Mask
CMYK* CMYK rw+ Raw cyan, magenta, yellow, and black samples
CMYKA* CMYK rw+ Raw cyan, magenta, yellow, black, and alpha samples
CR2 DNG r-- Canon Digital Camera Raw Image Format
CRW DNG r-- Canon Digital Camera Raw Image Format
CUR* ICON rw- Microsoft icon
CUT* CUT r-- DR Halo
DATA* INLINE rw+ Base64-encoded inline images
DCM* DCM r-- Digital Imaging and Communications in Medicine image
DICOM is used by the medical community for images like X-rays. The
specification, "Digital Imaging and Communications in Medicine
(DICOM)", is available at http://medical.nema.org/. In particular,
see part 5 which describes the image encoding (RLE, JPEG, JPEG-LS),
and supplement 61 which adds JPEG-2000 encoding.
DCR DNG r-- Kodak Digital Camera Raw Image File
DCX* PCX rw+ ZSoft IBM PC multi-page Paintbrush
DDS* DDS rw+ Microsoft DirectDraw Surface
DFONT* TTF r-- Multi-face font package (Freetype 2.6.0)
DNG DNG r-- Digital Negative
DOT DOT --- Graphviz
DPX* DPX rw- SMPTE 268M-2003 (DPX 2.0)
Digital Moving Picture Exchange Bitmap, Version 2.0.
See SMPTE 268M-2003 specification at http://www.smtpe.org
DXT1* DDS rw+ Microsoft DirectDraw Surface
DXT5* DDS rw+ Microsoft DirectDraw Surface
EPDF PDF rw- Encapsulated Portable Document Format
EPI PS rw- Encapsulated PostScript Interchange format
EPS PS rw- Encapsulated PostScript
EPS2* PS2 -w- Level II Encapsulated PostScript
EPS3* PS3 -w+ Level III Encapsulated PostScript
EPSF PS rw- Encapsulated PostScript
EPSI PS rw- Encapsulated PostScript Interchange format
EPT EPT rw- Encapsulated PostScript with TIFF preview
EPT2 EPT rw- Encapsulated PostScript Level II with TIFF preview
EPT3 EPT rw+ Encapsulated PostScript Level III with TIFF preview
ERF DNG r-- Epson Raw Format
FAX* FAX rw+ Group 3 FAX
FAX machines use non-square pixels which are 1.5 times wider than
they are tall but computer displays use square pixels, therefore
FAX images may appear to be narrow unless they are explicitly
resized using a geometry of "150x100%".
FITS* FITS rw- Flexible Image Transport System
FRACTAL* PLASMA r-- Plasma fractal image
FTS* FITS rw- Flexible Image Transport System
G3* FAX rw- Group 3 FAX
GIF* GIF rw+ CompuServe graphics interchange format
GIF87* GIF rw- CompuServe graphics interchange format (version 87a)
GRADIENT* GRADIENT r-- Gradual linear passing from one shade to another
GRAY* GRAY rw+ Raw gray samples
GROUP4* TIFF rw- Raw CCITT Group4
GV DOT --- Graphviz
H* MAGICK -w- Image expressed as a 'C/C++' char array
HALD* HALD r-- Identity Hald color lookup table image
HDR* HDR rw+ Radiance RGBE image format
HISTOGRAM* HISTOGRAM -w- Histogram of the image
HRZ* HRZ rw- Slow Scan TeleVision
HTM* HTML -w- Hypertext Markup Language and a client-side image map
HTML* HTML -w- Hypertext Markup Language and a client-side image map
ICB* TGA rw- Truevision Targa image
ICO* ICON rw+ Microsoft icon
ICON* ICON rw- Microsoft icon
IIQ DNG r-- Phase One Raw Image Format
INFO INFO -w+ The image format and characteristics
INLINE* INLINE rw+ Base64-encoded inline images
IPL* IPL rw+ IPL Image Sequence
ISOBRL* BRAILLE -w- ISO/TR 11548-1 format
JNG* PNG rw- JPEG Network Graphics
See http://www.libpng.org/pub/mng/ for details about the JNG
format.
JNX* JNX r-- Garmin tile format
JPE* JPEG rw- Joint Photographic Experts Group JFIF format (80)
JPEG* JPEG rw- Joint Photographic Experts Group JFIF format (80)
JPG* JPEG rw- Joint Photographic Experts Group JFIF format (80)
JPS* JPEG rw- Joint Photographic Experts Group JFIF format (80)
JSON JSON -w+ The image format and characteristics
K25 DNG r-- Kodak Digital Camera Raw Image Format
KDC DNG r-- Kodak Digital Camera Raw Image Format
LABEL* LABEL r-- Image label
M2V MPEG rw+ MPEG Video Stream
M4V MPEG rw+ Raw MPEG-4 Video
MAC* MAC r-- MAC Paint
MAGICK* MAGICK rw- Predefined Magick Image (LOGO, ROSE, etc.); output same as 'H'
MAP* MAP rw- Colormap intensities and indices
MASK* MASK rw+ Image Clip Mask
MAT MAT rw+ MATLAB level 5 image format
MATTE* MATTE -w+ MATTE format
MEF DNG r-- Mamiya Raw Image File
MIFF* MIFF rw+ Magick Image File Format
MKV MPEG rw+ Multimedia Container
MNG* PNG rw+ Multiple-image Network Graphics (libpng 1.6.18)
See http://www.libpng.org/pub/mng/ for details about the MNG
format.
MONO* MONO rw- Raw bi-level bitmap
MOV MPEG rw+ MPEG Video Stream
MP4 MPEG rw+ MPEG-4 Video Stream
MPC* MPC rw+ Magick Persistent Cache image format
MPEG MPEG rw+ MPEG Video Stream
MPG MPEG rw+ MPEG Video Stream
MRW DNG r-- Sony (Minolta) Raw Image File
MSL* MSL rw+ Magick Scripting Language
MSVG SVG rw+ ImageMagick's own SVG internal renderer
MTV* MTV rw+ MTV Raytracing image format
MVG* MVG rw- Magick Vector Graphics
NEF DNG r-- Nikon Digital SLR Camera Raw Image File
NRW DNG r-- Nikon Digital SLR Camera Raw Image File
NULL* NULL rw- Constant image of uniform color
ORF DNG r-- Olympus Digital Camera Raw Image File
OTB* OTB rw- On-the-air bitmap
OTF* TTF r-- Open Type font (Freetype 2.6.0)
PAL* UYVY rw- 16bit/pixel interleaved YUV
PALM* PALM rw+ Palm pixmap
PAM* PNM rw+ Common 2-dimensional bitmap format
PANGO* PANGO --- Pango Markup Language
PATTERN* PATTERN r-- Predefined pattern
PBM* PNM rw+ Portable bitmap format (black and white)
PCD* PCD rw- Photo CD
PCDS* PCD rw- Photo CD
PCL PCL rw+ Printer Control Language
PCT* PICT rw- Apple Macintosh QuickDraw/PICT
PCX* PCX rw- ZSoft IBM PC Paintbrush
PDB* PDB rw+ Palm Database ImageViewer Format
PDF PDF rw+ Portable Document Format
PDFA PDF rw+ Portable Document Archive Format
PEF DNG r-- Pentax Electronic File
PES* PES r-- Embrid Embroidery Format
PFA* TTF r-- Postscript Type 1 font (ASCII) (Freetype 2.6.0)
PFB* TTF r-- Postscript Type 1 font (binary) (Freetype 2.6.0)
PFM* PFM rw+ Portable float format
PGM* PNM rw+ Portable graymap format (gray scale)
PICON* XPM rw- Personal Icon
PICT* PICT rw- Apple Macintosh QuickDraw/PICT
PIX* PIX r-- Alias/Wavefront RLE image format
PJPEG* JPEG rw- Joint Photographic Experts Group JFIF format (80)
PLASMA* PLASMA r-- Plasma fractal image
PNG* PNG rw- Portable Network Graphics (libpng 1.6.18)
See http://www.libpng.org/ for details about the PNG format.
PNG00* PNG rw- PNG inheriting bit-depth, color-type from original if possible
PNG24* PNG rw- opaque or binary transparent 24-bit RGB (zlib 1.2.5)
PNG32* PNG rw- opaque or transparent 32-bit RGBA
PNG48* PNG rw- opaque or binary transparent 48-bit RGB
PNG64* PNG rw- opaque or transparent 64-bit RGBA
PNG8* PNG rw- 8-bit indexed with optional binary transparency
PNM* PNM rw+ Portable anymap
PPM* PNM rw+ Portable pixmap format (color)
PREVIEW* PREVIEW -w- Show a preview an image enhancement, effect, or f/x
PS PS rw+ PostScript
PS2* PS2 -w+ Level II PostScript
PS3* PS3 -w+ Level III PostScript
PSB* PSD rw+ Adobe Large Document Format
PSD* PSD rw+ Adobe Photoshop bitmap
PTIF* TIFF rw+ Pyramid encoded TIFF
PWP* PWP r-- Seattle Film Works
RADIAL-GRADIENT* GRADIENT r-- Gradual radial passing from one shade to another
RAF DNG r-- Fuji CCD-RAW Graphic File
RAS* SUN rw+ SUN Rasterfile
RAW DNG r-- Raw
RGB* RGB rw+ Raw red, green, and blue samples
RGBA* RGB rw+ Raw red, green, blue, and alpha samples
RGBO* RGB rw+ Raw red, green, blue, and opacity samples
RGF* RGF rw- LEGO Mindstorms EV3 Robot Graphic Format (black and white)
RLA* RLA r-- Alias/Wavefront image
RLE* RLE r-- Utah Run length encoded image
RMF DNG r-- Raw Media Format
RW2 DNG r-- Panasonic Lumix Raw Image
SCR* SCR r-- ZX-Spectrum SCREEN$
SCT* SCT r-- Scitex HandShake
SFW* SFW r-- Seattle Film Works
SGI* SGI rw+ Irix RGB image
SHTML* HTML -w- Hypertext Markup Language and a client-side image map
SIX* SIX rw- DEC SIXEL Graphics Format
SIXEL* SIXEL rw- DEC SIXEL Graphics Format
SPARSE-COLOR* TXT -w+ Sparse Color
SR2 DNG r-- Sony Raw Format 2
SRF DNG r-- Sony Raw Format
STEGANO* STEGANO r-- Steganographic image
SUN* SUN rw+ SUN Rasterfile
SVG SVG rw+ Scalable Vector Graphics (XML 2.9.2)
SVGZ SVG rw+ Compressed Scalable Vector Graphics (XML 2.9.2)
TEXT* TXT rw+ Text
TGA* TGA rw- Truevision Targa image
THUMBNAIL* THUMBNAIL -w+ EXIF Profile Thumbnail
TIFF* TIFF rw+ Tagged Image File Format (LIBTIFF, Version 4.0.6)
TIFF64* TIFF rw- Tagged Image File Format (64-bit) (LIBTIFF, Version 4.0.6)
TILE* TILE r-- Tile image with a texture
TIM* TIM r-- PSX TIM
TTC* TTF r-- TrueType font collection (Freetype 2.6.0)
TTF* TTF r-- TrueType font (Freetype 2.6.0)
TXT* TXT rw+ Text
UBRL* BRAILLE -w- Unicode Text format
UIL* UIL -w- X-Motif UIL table
UYVY* UYVY rw- 16bit/pixel interleaved YUV
VDA* TGA rw- Truevision Targa image
VICAR* VICAR rw- VICAR rasterfile format
VID* VID rw+ Visual Image Directory
VIFF* VIFF rw+ Khoros Visualization image
VIPS* VIPS rw+ VIPS image
VST* TGA rw- Truevision Targa image
WBMP* WBMP rw- Wireless Bitmap (level 0) image
WMV MPEG rw+ Windows Media Video
WPG* WPG r-- Word Perfect Graphics
X3F DNG r-- Sigma Camera RAW Picture File
XBM* XBM rw- X Windows system bitmap (black and white)
XC* XC r-- Constant image uniform color
XCF* XCF r-- GIMP image
XPM* XPM rw- X Windows system pixmap (color)
XPS XPS r-- Microsoft XML Paper Specification
XV* VIFF rw+ Khoros Visualization image
YCbCr* YCbCr rw+ Raw Y, Cb, and Cr samples
YCbCrA* YCbCr rw+ Raw Y, Cb, Cr, and alpha samples
YUV* YUV rw- CCIR 601 4:1:1 or 4:2:2
* native blob support
r read support
w write support
+ support for multiple images
その他できること
ImageMagickを使うと、フォーマットの変換だけでなく画像サイズの変換やフィルターをかける事もできるようです。
http://www.envinfo.uee.kyoto-u.ac.jp/user/susaki/image/magick_process.html
